PS6K, also known as RPS6KB1, is a serine/threonine-protein kinase. It belongs to the RSK (ribosomal s6 kinase) family. Members of this family function in signal transduction. PS6K is an isoform of p70 ribosomal S6 kinase (S6K). S6K can be activated by mitogenic stimuli such as growth factors, insulin and cytokines. It phosphorylates the ribosomal protein S6. PS6K also phosphorylates other proteins such as elF4B, eEF2K and SKAR. It is a crucial effector of mTOR(rapamycin) signaling. PS6K is dissociated from the EIF3 complex and activated upon mitogenic stimulation, phosphorylation by the mammalian target of mTOR complex 1 (mTORC1). Its active form then phosphorylates and activates several substrates in the preinitiation complex, including the EIF2B complex and the cap-binding complex component EIF4B. PS6K also functions in cell proliferation, cell growth and cell cycle progression.

Ribosomal protein S6 kinase alpha-2, also known as 9 kDa ribosomal protein S6 kinase 2, MAP kinase-activated protein kinase 1c, MAPK-activated protein kinase 1c, Ribosomal S6 kinase 3, RSK-3, RPS6KA2 and MAPKAPK1C, is a nucleus protein that belongs to the protein kinase superfamily, AGC Ser/Thr protein kinase family and S6 kinase subfamily. RPS6KA2 / RSK-3 is expressed in many tissues. Highest expression is in lung and skeletal muscle. The expression of RPS6KA2 reduced proliferation, caused G1 arrest, increased apoptosis, reduced levels of phosphorylated extracellular signal-regulated kinase and altered other cell cycle proteins. RPS6KA2 / RSK-3 contains one AGC-kinase C-terminal domain and two protein kinase domains. It forms a complex with either ERK1 or ERK2 in quiescent cells. It transiently dissociates following mitogenic stimulation. RPS6KA2 / RSK-3 is a serine/threonine kinase that may play a role in mediating the growth-factor and stress induced activation of the transcription factor CREB. RPS6KA1, RPS6KA2, RPS6KB1, RPS6KB2, and PDK1 are involved in several pathways central to the carcinogenic process, including regulation of cell growth, insulin, and inflammation.

RHEB is a recently discovered member of the Ras superfamily that may be involved in neural plasticity. This function is novel and not typically associated with the Ras proteins. RHEB gene is a member of the small GTPase superfamily and encodes a lipid-anchored, cell membrane protein with five repeats of the RAS-related GTP-binding region. RHEB is vital in regulation of growth and cell cycle progression due to its role in the insulin / TOR / S6K signaling pathway. The protein has GTPase activity and shuttles between a GDP-bound form and a GTP-bound form, and farnesylation of RHEB is required for this activity. Three pseudogenes have been mapped, two on chromosome 1 and one on chromosome 22.

GTP-Binding Protein Rheb (RHEB) is a member of the small GTPase superfamily and encodes a lipid-anchored, cell membrane protein with five repeats of the RAS-related GTP-binding region. Highest levels of RHEB can be found in the skeletal and cardiac muscle, and it is vital in the regulation of growth and cell cycle progression due to its role in the Insulin/TOR/S6K signaling pathway. RHEB stimulates the phosphorylation of S6K1 and EIF4EBP1 through activation of mTORC1 signaling, and it activates the protein kinase activity of mTORC1. RHEB has GTPase activity and shuttles between a GDP-bound form and a GTP-bound form, farnesylation of the protein is required for this activity.