Equal division of the physical cell directly influences the transfer of a complete set of chromosomes from one cell generation to the next. Therefore, it is imperative for cancer prevention that the cell division process is strictly regulated. In fission yeast and human cells, an actomyosin based contractile ring assembles at the medial region of the cell during mitosis and spatially dictates where the cell will physically separate. However, the molecular mechanisms that contribute to proper ring formation and function are unclear. The long- term goal of this project is to elucidate the regulatory controls necessary for a fully functional ring. Our preliminary results indicate that in fission yeast the Cdc14-like phosphatase, Clplp, interacts with Midlp, an anillin homolog required for correct ring placement. Utilizing biochemical assays and molecular imaging tech- niques, the objective of this application is to characterize these two ring components and their interaction in order to understand the contractile ring at a molecular level. It is expected that examining conserved proteins and molecular mechanisms that contribute to faithful cell division in simple systems will expedite the generation of knowledge necessary to significantly improve our understanding of cell division in higher organisms. [unreadable] [unreadable]