Binds GTP and exhibits intrinsic GTPase activity (By similarity). May activate NF-kappa-B-mediated gene transcription (PubMed:16328882). Promotes signal transduction through MTOR, activates RPS6KB1, and is a downstream target of the small GTPase-activating proteins TSC1 and TSC2. {ECO:0000250|UniProtKB:Q15382, ECO:0000269|PubMed:12869548, ECO:0000269|PubMed:16098514, ECO:0000269|PubMed:16328882, ECO:0000269|PubMed:17162089}. This is the function of Ensembl gene identifier ENSG00000167550 (RHEBL1, RHEB like 1).