The award recognizes McMahon’s career advancing developmental biology and building scientific communities, including USC Stem Cell.

As a pioneer in developmental biology and founder of USC Stem Cell, Andy McMahon, PhD, FRS, does not attribute his success to being smart.

“I’m certainly not naturally smart,” said McMahon, who tends toward understatement. “I’m very interested in certain things, and I’ve been helped by being able to focus deeply into the problems that interest me.”

McMahon, a 2026 USC Faculty Lifetime Achievement Award recipient, has applied this focus to problems ranging from understanding mammalian development to building a university-wide USC Stem Cell initiative.

“You have to have a balance here, where you can focus enough on something to make good progress and insight into that problem,” he said. “But then you have to lift your head up every now and then, and look more broadly beyond that problem to see what the significance is in a much more general way.”

This approach has guided McMahon’s career.

Today, USC Stem Cell connects over 100 research and clinical faculty across USC and Children’s Hospital Los Angeles (CHLA), bringing together scientists, engineers and clinicians to develop new stem cell-based therapies.

“It’s a conceptual thing, not an actual thing,” said USC University Professor Emeritus McMahon, who was the founding chair of the Department of Stem Cell Biology and Regenerative Medicine, and director of the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at USC from 2012 until 2024.

“The important thing was to make it so that we weren’t this isolated bunch of people,” added McMahon, who is now a research professor of biology and biological engineering at Caltech. “To grow, this area needs to have the input of lots of different people. If you’re a computer scientist, if you’re an engineer, if you’re a chemist, it doesn’t matter. You’re putting your effort into this USC Stem Cell-wide effort, and so you can be part of it.”

A scientist by nature

McMahon’s deep focus on the problems that interest him runs through every stage of his career.

The fourth of five children, he grew up in Birkenhead, a working-class shipbuilding town across the River Mersey from Liverpool. His father apprenticed as an accountant at 15, and his mother was a homemaker who later became a public librarian.

“I was thinking about this the other day,” said McMahon. “Many of my colleagues had an example of academia or university running close to their family, and I had no example of that. So I had no idea about what being a scientist was.”

Even so, there were signs that McMahon might be destined for this career.

“I always had a very strong interest in life,” said McMahon, who bred tropical fish for fun. “I started out with a general interest in animals, and then in the 70s, got a lot into ecology and the environment.”

At 17, he turned that focus to gaining early entrance to Oxford University.

“I decided myself, without any advice from the school that I was in, to put myself down to take this exam,” he said. “And I don’t think anybody considered that I was good enough to get into Oxford. It was actually against the wishes of the headmaster of my school who, in front of the entire class, said, ‘If you think I’m going to do anything to help you get into Oxford, then you’ve got another thought coming.’ ”

Excused from classes for a semester to prepare, McMahon spent his time in the library reading about molecular biology, genetics and development, and discovered his lifelong scientific obsession.

“I’m not sure that I’ve ever seen a good answer to that question of what interests one person but bores another,” he said. “To me, it’s a fundamentally, astonishingly, fascinatingly interesting question, as to how a fertilized egg generates all the different cell types of our body. I just can’t imagine not being interested in that question.”

Oxford admitted him as an undergraduate studying zoology. He then pursued his PhD at the Medical Research Council (MRC) at University College London.

“I thought deeply about the science I was doing, but not my career as such,” he said. “Somehow or other, it took care of itself. It’s like I’ve been a magic acrobat, in which I do some tumble that I’ve never tried before, and I land straight on my feet.”

To learn to clone genes and study their role in development, McMahon moved to Caltech for his postdoctoral training in the sea urchin laboratory of Eric Davidson, PhD.

“I had no idea that Caltech was such a fabulous place until I got there, and a very humbling place,” said McMahon. “Because I came there as this person with a PhD from the UK, and that PhD was something I got in three years. And then I met some of these graduate students at Caltech who were so much more accomplished than me. And these fabulous connections with people have been long-life connections.”

Partners in life and science

During his postdoc, Andy made another lifelong connection in Jill. The two met during the 1983 meeting of the West Coast Society for Developmental Biology at Asilomar in Pacific Grove, California. Although she was a PhD student at the University of Colorado Denver and lived more than 1,000 miles away, they started a long-distance relationship.

After dating for 11 months, which amounted to a total of 20 days together, Andy and Jill made the mutual decision to get married.

“We decided to go to Mexico, to the Yucatan, at the Christmas after we met in April. It was a discussion in a pleasant hotel. We both said, ‘Well, I think you’re the one, and should we get married?’ ”

Back in Los Angeles, they lined up at the courthouse to be married.

After completing his postdoc and teaching a summer embryology course at Woods Hole, Massachusetts, Andy accepted a position as a staff scientist at MRC’s National Institute for Medical Research (NIMR) in Mill Hill in London. Jill exited her PhD program early with a master’s degree and started a job at the Imperial Cancer Research Fund, so they could be together.

At NIMR in Mill Hill, Andy began studying signaling proteins called Wnts. While these proteins were known to drive cancer, their role in normal development remained mysterious. By studying Wnts in the embryo, Andy showed how they coordinate cells to establish the body axis from head to tail, and contribute to brain development.

After four years in the UK, the McMahons returned to the US when Andy joined the Roche Institute of Molecular Biology in Nutley, New Jersey. At an industry-funded institute designed to operate like an academic research environment, he had the resources and freedom to pursue fundamental biological questions without the constant pressure of writing grants.

It was at Roche that Jill first joined the McMahon Lab as a research scientist and lab manager. Although they were initially skeptical about working together, Andy calls it “a fabulous decision.”

“We figured we’d lived together now for four years, and we learned that we can do that, so maybe we could actually work together in the lab,” he said. “That has been another incredibly lucky thing. I have had, as my closest working partner, somebody who I get along with so well and is so good at the work they’re doing. And I could enjoy it even more, because of the fact that this person is my partner.”

While at Roche, the McMahons also welcomed their first child Samantha. Andy jokes that they might have achieved a “work-life imbalance,” but the new parents made it work by taking turns covering each other’s experiments and parenting. Samantha also had the opportunity to travel all over the world to scientific meetings, as did her younger brother Sean, born nine years later.

“We really enjoy travel, and being in science allows you to meet people that are all over the world,” said Jill, who spent part of her childhood growing up in Pakistan and Iran. “That’s been a wonderful thing for our kids. I think Sean is the only one who has been babysat by two Nobel Prize winners.”

Andy added: “That’s also one of the things that has bound us. We both like travel. We just came back from a week’s walk in the UK, the Dales High Way in Yorkshire, which is like a 90-mile walk. It’s just so amazing how much we see things so similarly, like how a stone wall is shining when the sun comes on it. We both get excited by things like that, so we’re very much soulmates in that respect.”

The Harvard years

When Samantha was four, McMahon was recruited to Harvard University.

“A university is very different from a research institution,” he said. “A research institution usually has a tight focus. A university, if it’s a good one, has a breadth of foci, and a much more interesting environment to learn unexpected things, think unexpected thoughts, get unexpected input from people.”

He collaborated with Phil Ingham, PhD, FRS, at the Imperial Cancer Research Fund and Cliff Tabin, PhD, at Harvard to identify the vertebrate versions of the signaling protein family known as hedgehog, including Sonic hedgehog. In a series of landmark papers published in the journal Cell in 1993, they showed that these proteins act as morphogens, signals that shape developing vertebrate embryos.

With Harvard colleague Doug Melton, PhD, and others, he co-founded the biotech company Ontogeny, now named Curis. Based on their work with hedgehog, the company licensed technology to Genentech that led to an FDA-approved therapy for rare invasive forms of basal cell carcinoma of the skin.

In addition to these scientific advances, McMahon played a major role in building Harvard’s stem cell program. He was chair of the Department of Molecular and Cellular Biology, a founding member of the Department of Stem Cell and Regenerative Biology, and a principal investigator of the Harvard Stem Cell Institute.

With Melton, he also embarked on a project to generate new human embryonic stem cell lines for the research community. Because federal funding could not be used to derive such lines, Melton drew on his Howard Hughes Medical Institute support, while Jill McMahon lent her expertise.

“I deemed that this was so important that actually Jill left my lab and moved to Doug’s lab to generate the first human embryo stem cell lines at Harvard,” said McMahon.

After 19 productive years at Harvard, another interesting problem attracted his focus and drew him to USC.

“I left Harvard because I wanted to do something different,” he said. “I remember when I talked to the dean and my department chair, they said, ‘Well, what’s it going to take to keep you?’ And I said, ‘That’s not what this is about. This is about going to a different university to do something I can’t do at Harvard.’ And they were incredibly supportive when they understood the reason why I wanted to go.”

The directed differentiation of USC

At USC, McMahon recognized the opportunity to shape a place earlier in its development. If the Harvard Stem Cell Institute was the establishment, the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at USC offered potential.

“Harvard is a mature beast,” said McMahon. “At USC, there was a core of cool, wonderful people who you could work with in building up a much larger organization at a time where these exciting, young, talented people were coming out from these great labs and looking for a new place to go. So this was exactly the right time to do something significant in this area and not bring in established hot shots, but bring in young scientists. And that’s a far more attractive mechanism to me of building a sustainable community of first-rate scientists.”

Two years after USC’s stem cell building opened, McMahon took the helm of the research center it housed. He founded the Department of Stem Cell Biology and Regenerative Medicine, and launched the USC Stem Cell initiative.

USC Stem Cell provided around $4 million to fund multidisciplinary research collaborations across USC, CHLA and Caltech. Many of these projects went on to attract many times that amount in continuing grant funding.

He also led the recruitment of a cohort of early career faculty through an open, collective hiring process. The result was a culture where colleagues supported each other and good ideas could come from anywhere.

“When I had my one-on-one interviews with our potential recruits, I stressed that this is a community built on mutual respect and trust, and we’ll only grow and be a really strong group if we’re collaborative and collegial,” he said.

These faculty established their labs and moved their research programs towards clinical trials for diseases ranging from ALS to arthritis. They brought in partners from the biotech industry and spun off startups. The CIRM-funded USC+CHLA Alpha Clinic and USC/CHLA cell manufacturing facility provided additional support for translating discoveries into cell and gene therapies.

McMahon made it a priority to recruit faculty dedicated not only to research, but also to education.

“I felt like we wanted to have a culture that really embraced education at all levels as a uniting component that brought together the faculty,” said McMahon. “It was very key to be able to have a whole pipeline of trainees, from undergraduate—we established a unique master’s program—to PhD to postdoctoral fellows. And that process of teaching shapes your own research.”

Key to this mission was launching a first-of-its-kind master’s program in stem cell biology and regenerative medicine in 2014, bridging a gap in training at USC and beyond.

“I would say that in my career, of anything I’ve been involved with, I’m most pleased by what’s happened with the master’s program,” said McMahon.

Francesca Mariani, PhD, faculty director of the master’s program, credits McMahon’s “clarity of vision” in building both a scientific and educational community.

“As chair, he focused on building a world-class department of innovative scientists and was also a highly regarded teacher committed to advancing education,” she said. “His legacy extends beyond his scientific contributions to the culture of excellence and intellectual discipline he instilled, and to the many students and trainees he mentored.”

At the undergraduate level, McMahon taught the flagship course in regenerative medicine. He also encouraged and supported a stem cell minor, complemented by a CIRM-funded program called COMPASS that prepares juniors and seniors for careers in the field.

This critical educational pipeline extends to local middle and high school students who experience USC’s stem cell research center through enrichment programs and outreach events.

McMahon also invested in shared research facilities for optical imaging, genome engineering and more, benefiting the broader research community.

In addition, USC Stem Cell offers a weekly seminar series as well as departmental retreats, and has hosted cross-institutional symposia and even the 2019 meeting of the International Society for Stem Cell Research (ISSCR) that convened more than 3,000 scientists at the Los Angeles Convention Center with support from the Choi family.

“I’m incredibly grateful, of course, to all the philanthropic supporters, in particular Eli and Edythe Broad and the Choi family, for their investment,” said McMahon. “This could not have happened without those people’s faith and trust in us.”

McMahon noted that the success of USC Stem Cell relied on the contributions of staff across the University, from strategic initiatives and communications to administration, including Qing Liu-Michael, PhD, Juliane Glaeser, PhD, Kim Price and Ellen Pascual.

Gage Crump, PhD, vice-chair of USC’s stem cell department, observes that McMahon’s leadership approach takes a cue from his hobby of running.

“When we were at the LA Basin stem cell retreat at Lake Arrowhead, Andy, an avid runner, went out for a jog around the lake,” said Crump. “Once he got part of the way around the lake, he realized it would be much farther than he anticipated. Rather than turning back, he ended up running more than 20 miles. This embodies Andy’s dedication to our stem cell center and department. He always had boundless energy and went the extra mile to make our stem cell center what it is today.”

Despite his natural modesty, McMahon can also appreciate the legacy he’s built.

“Overall, it makes me smile when I come in, and I see all these new people who I don’t even know who they are, working away in the labs of people who I do know,” he said. “And then I see what’s coming out of those labs in research, and it’s very exciting.”

Building a kidney

While he was building USC Stem Cell, McMahon had a new idea for his lab. Having spent his career studying organ development in the embryo, he wanted to shift his focus to kidney repair and regeneration in the adult.

While mid-career pivots can be difficult to fund, he secured $5.7 million from the California Institute for Regenerative Medicine (CIRM) through its Research Leadership award, designed to attract established investigators entering new scientific territory.

“What he did when he came to USC, it’s an interesting strategy,” said Nils Lindström, PhD, who joined the McMahon Lab as a postdoc in 2015 and is now an assistant professor of stem cell biology and regenerative medicine at USC. “He went from Harvard, and he had this multi-system lab with all these different ideas, and then went kidney. He has said himself that the reason for that is because if you’re going to make a meaningful impact on one system, the kidney is the one that needs to be worked on right now.”

As a postdoc, Lindström authored eight first-author papers that laid out the blueprints for how the human kidney develops, informing the field’s broader efforts to grow miniature kidney-like structures called organoids in the lab.

“The ability to have so many different systems in his head at the same time and work with very clever people in these various systems then allowed him to look at the kidney in a new way,” he said. “It was not just, ‘I’m a kidney person, and here are my gradual, incremental insights that I make.’ It’s like, ‘This happens in the brain. That is evidently happening in the kidney.’ He knew about the problem from so many different angles.”

For Lindström and others, McMahon’s mentorship extended beyond the lab.

“I kept being invited into their home every time I was trying to figure out where to move,” said Lindström. “During the evacuations from the fire, Jill phoned me before I even knew there was a fire saying to come over. I’ve probably stayed there for close to five months in total in my life, which is quite a lot of time to stay with your boss.”

The lab also improved models of acute kidney injury and identified key genetic drivers of progression to chronic kidney disease, opening new avenues of research.

In collaboration with USC kidney researchers including Lindström and Zhongwei Li, PhD, McMahon advanced the effort to build a lab-grown synthetic kidney for studying disease and eventually developing replacement organs.

In 2025, led by Li, the team published a paper in Cell Stem Cell describing the creation of kidney “assembloids,” the most mature and complex kidney structures ever grown in a lab.

McMahon also contributed to national efforts such as the GenitoUrinary Development Molecular Anatomy Project (GUDMAP) and the NIH-funded Re(Building) a Kidney, collaborative consortia that share data, tools and expertise across the field.

“He always had time for every member of our center, from junior faculty to master’s students and undergraduates,” said Crump. “You could count on Andy to be excited about your science and give thoughtful and insightful feedback on where to go. His legacy will be the hundreds of mentees that follow in his footsteps.”

A new model system

After leading USC Stem Cell for over a decade, McMahon decided that it was time to focus deeply on something else.

“I do feel rather strongly that people overstay their positions in leadership,” he said. “When one gets really comfortable with a position, it’s likely to lose its edge a little bit. And the second thing is you’ve got to give younger people a chance at leadership.”

In 2024, McMahon retired from USC and welcomed physician-scientist Chuck Murry, MD, PhD, as the new director and chair.

“Andy McMahon is a scientist’s scientist,” said Murry. “As a leader, he built one of the nation’s top stem cell programs, recruiting a cadre of talented scholars and setting the stage for USC to become a leader in human regenerative medicine. I’m proud to call him a colleague, a mentor and a friend.”

Meanwhile, McMahon returned to his postdoctoral training ground, Caltech, to pursue a new approach: a lab in which every trainee is co-mentored in a second lab.

“I’m still excited in science, particularly the kidney area, and I’m very interested in interacting with people across different disciplines,” he said. “That’s why I came to Caltech with a view to a very different type of a lab, where I have almost no lab, but my job is to try and convince people who do have labs that the approaches that they’re applying to science could be equally as well, if not better applied to systems that I’m familiar with.”

Now that Jill is retired from the lab and exploring her interests in education and painting, the couple has more time to travel and enjoy their first grandchild, Samantha’s daughter Reya.

He remains as deeply focused on the problems that interest him as he was when he first read about molecular biology, genetics and developmental biology as a student.