These studies point out the importance of hyperproliferating A-IC cells that express both Tsc1 and Tsc2 proteins and therefore should have a functional TSC-RHEB-mTORC1 axis in TSC cystogenesis [9,10], a pattern that is also observed in the epithelium of renal cysts in TSC patients [11]. The gene discussed is RHEB; the disease is cystic kidney disease.