TSC2 and digestive system neoplasm: TSC2 is a target of RAS/ERK signaling, and direct phosphorylation of tuberous sclerosis complex 2 (TSC2) by ERK leads to suppression of tumor-suppressive functions.44 A study of 63 colon carcinomas45 showed that approximately one-third of colon carcinomas were positive for phosphorylated TSC2.