I am a Graduate student in the Koff Lab. Studies that examined the regulation of the cdk inhibitor, p21, in PDGF-induced oligodendrogliomas led to the identification of a novel E3 ligase. Data indicates that this E3 ligase regulates p21 accumulation in this system in a ubiquitin-dependent manner. My research aims at understanding the mechanism of action of this E3 ligase. What are the specific substrate requirements? What are the protein interactions involved? What are the molecular requirements of the E3 ligase? In order to address such questions, one of my primary focuses is to reconstitute the ubiquitination process in vitro. This in vitro approach along with studies in vivo will provide an insight into this novel mechanism of p21 regulation.