High Quality Content by WIKIPEDIA articles! PTEN (for `phosphatase and tensin homologue deleted on chromosome 10`), which encodes for the PTEN protein (or phosphatidylinositol-3,4,5-triphosphate 3-phosphatase), acts as a tumor suppressor gene through action of its phosphatase protein product. Cells that lack PTEN are unable to regulate the PtdIns 3-kinase programme, which stimulates a variety of cellular phenotypes that favour oncogenesis. The phosphatase protein performs a regulatory role within the cell cycle, preventing uncontrolled growth and division of cells. Mutation of the gene consequently results in tumor formation and is observed in large number of cancers at high frequency.