Tjian is a professor of biochemistry and molecular biology at the University of California, Berkeley. Trained as a biochemist, he has made major contributions to the understanding of how genes work during three decades at Berkeley. He was named an HHMI investigator in 1987 and served as president of the Howard Hughes Medical Institute from 2009 until 2016. Tjian studies the biochemical steps involved in controlling how genes are turned on and off, key steps in the process of decoding the human genome. He discovered proteins called transcription factors that bind to specific sections of DNA and play a critical role in controlling how genetic information is transcribed and translated into the thousands of biomolecules that keep cells, tissues, and organisms alive. His laboratory has illuminated the relationship between disruptions in the process of transcription and human diseases such as cancer, diabetes, and Huntington’s disease. More recently, he has begun studying how transcription factors control the differentiation of embryonic stem cells into muscle, liver, and neurons. Tjian received a bachelor’s degree in biochemistry from Berkeley and a Ph.D. from Harvard University. After completing a postdoctoral fellowship at the Cold Spring Harbor Laboratory with James Watson, he joined the Berkeley faculty in 1979. He is a member of the National Academy of Sciences, and has received many awards honoring his scientific contributions, including the Alfred P. Sloan Prize from the General Motors Cancer Research Foundation, and the Louisa Gross Horwitz Prize from Columbia University. He was named California Scientist of the Year in 1994.