Inappropriate cell proliferation is a hallmark of cancer. In a normal cell, the decision to divide is tightly regulated at multiple levels. However, this control is eroded in cancerous cells, as mutations in tumor suppressor genes remove the checks to restrain proliferation. The research in my laboratory is focused on the retinoblastoma (RB) tumor suppressor pathway, which regulates cell proliferation, differentiation and apoptosis and is inactivated in almost all human cancers. The overarching goal of our research is to identify the specific functions of the RB pathway that are important during normal animal development and why the loss of these functions is one of the key events in cancer. We employ biochemical, genetic and genomics approaches towards this goal. Recently, we set up a pipeline for single cell RNA sequencing. This platform can be used to understand the source of tumor heterogeneity and therefore could have a great impact on the design of therapeutic strategies.