The major focus of our laboratory is to study the role of the Rb-binding protein RIZ1 as a tumor suppressor involved in the Rb-p53 pathway. RIZ1 is a member of the PR/SET domain superfamily of nuclear proeins functioning in chromatin mediated gene expression. RIZ1 causes G2/M cell cycle arrest and/or apoptosis. We are using cell culture and animal models to investigate a putative Rb-RIZ1-p53 pathway in the control of cell cycle and apoptosis.