sentences:  FLCN acts as a GTPase-activating protein (GAP) toward Rag C/D GTPases, members of another Ras-related GTP-binding protein family, which are necessary for amino acid-dependent mTORC1 activation at the lysosomal membrane.The heterodimeric Rag GTPases (RagA or B in complex with RagC or D) in a lysosome-associated complex with Ragulator and vacuolar adenosine triphosphatase (v-ATPase) interact with mTORC1 in response to amino acids from the lysosomal lumen to promote translocation of mTORC1 to the lysosomal surface for activation by the small GTPase Ras-homolog enriched in brain (Rheb).GTP-loading of RagA/B is a requirement for amino acid signaling to mTORC1.