Stephen J. Elledge, Ph.D., is a Professor of Genetics at Harvard Medical School. Dr. Elledge’s research has uncovered important clues about key biological pathways driving the cell cycle and how cells sense and respond to DNA damage. His research has also contributed to advances in scientific disciplines by developing new cloning methods, novel approaches to build cDNA libraries that could be expressed in yeast. Dr. Elledge has made instrumental discoveries isolating and identifying genes that play key roles in the development of various cancers, including p21 and p57. He and his colleagues’ research also led to important discoveries about how cells detect and repair DNA damage, uncovering a whole signal transduction mechanism that alerts cells to chromosome defects. He recently identified the Chk2 enzyme, which activates the tumor-suppressor p53 to prevent cells with damaged DNA from dividing. When this enzyme is missing or defective, the “brakes” on cell division are released, increasing the risk of cancer. Dr. Elledge holds a B.S. in Chemistry from the University of Illinois and a Ph.D. in Biology from the Massachusetts Institute of Technology (MIT).