Rabbit Anti-Human RPS6KA1 polyclonal antibody for WB, Inhib, IHC, IP. Ribosomal protein S6 kinase alpha-1 (EC 2.7.11.1; UniProt Q15418; also known as 90 kDa ribosomal protein S6 kinase 1, MAP kinase-activated protein kinase 1a, MAPK-activated protein kinase 1a, MAPKAP kinase 1a, MAPKAPK-1a, p90-RSK 1, p90RSK1, p90S6K, Ribosomal S6 kinase 1, RSK-1, S6K-alpha-1) is encoded by the RPS6KA1 (also known as MAPKAPK1A, RSK1) gene (Gene ID 6195) in human. Ribosomal s6 kinases (RSKs) are serine/threonine kinases that play a role in mediating Mek1/2-Erk1/2 mitogen-activated protein (MAP) kinase pathway signaling events. There exist two types of RSKs, p70rsk (a.k.a. S6 Kinase or S6-H1 kinase) and p90rsk (a.k.a. MAPK-activated protein kinase). Six p90rsk-coding genes have been identified in human, RPS6KA1 (MAPKAPK1A, RSK1), RPS6KA2 (MAPKAPK1C, RSK3), RPS6KA3 (MAPKAPK1B, RSK2), RPS6KA4 (MSK2), RPS6KA5 (MSK1), and RPS6KA6 (RSK4). Erk1/2 activates p90RSK1 by sequential phosphorylation events, where it first phosphorylates Rsk1 C-terminal kinase domain (CTKD) Thr573, leading to subsequent Ser380 phosphorylation in the N-terminal AGC kinase-type domain. Alternatively, Ser380 can be phosphorylated directly by MK2/3 independent of CTKD.