Dr. Stillman’s research focuses on how chromosomes, including both DNA and chromosome-associated proteins, are duplicated in human cells and in yeast, thereby ensuring accurate inheritance of genetic material from one generation to the next. Missteps in the process can lead to cancer. Dr. Stillman is most widely known for his groundbreaking discovery of the Origin Recognition Complex (ORC), the initiator protein complex that is universal among eukaryotes. His subsequent research determined how the initiation of chromosome replication occurs and how it is regulated. He also highlighted other functions of ORC proteins in cells, including controlling gene transcription and the duplication of centrosomes, structures that orchestrate chromosome separation during mitosis. Mutations in ORC have been linked to Meier–Gorlin syndrome, a condition that results in people with extreme dwarfism.
Each time a cell divides, it must copy its DNA equally into two new cells. If the cell’s DNA is not copied precisely before it divides, new cells end up without necessary genetic information which can prevent their division, lead to cell death, or cause many cells to divide out of control, forming a tumour.
By describing the exact sequence of events involved in DNA replication, Stillman and Diffley have provided key insights into how our genome is duplicated and how this process is coordinated with many other essential cellular events, which have implications for understanding genome instability and tumour heterogeneity in cancer.