Our laboratory studies how ubiquitin-dependent protein degradation controls cell cycle progression in normal and cancer cells. We are interested in the regulation of the Anaphase-Promoting Complex, a large multisubunit complex that targets many important mitotic regulators for destruction by the ubiquitin pathway. To study this problem, we apply biochemical reconstitution with small molecule inhibitors to dissect mechanism of action. We are also interested in how chromosome segregation is perturbed in cancer cells, and we employ long-term time lapse imaging to understand how normal cells and cancer cells cope with defects in chromosome segregation. We are also using siRNA screening approaches to identify genes that modulate the sensitivity of breast cancer cells to trastuzumab (herceptin).