Hamartin, or TSC1, is a suspected tumor suppressor implicated in the disease tuberous sclerosis 1. It is a negative regulator of cell division controlling the transition from G0/G1 to S phase, and it seems to act through the phosphatidylinositol 3 kinase/Akt pathway. TSC1 interacts with tuberin m(TSC2), which is thought to be a GAP (GTPase Activating Protein) for the Rap1 and Rab5 small G Proteins. The Hamartin/Tuberin complex has been shown to inhibit mTor. Hamartin has also been shown to interact with ERM (Ezrin-Radixin-Moesin) proteins and with F-actin, suggesting a role for TSC proteins in modulation of cell adhesion and morphology.