p70 S6 Kinase Substrates Antibody Sampler Kit #2903

p70 S6 kinase is a mitogen activated Ser/Thr protein kinase that is required for cell growth and G1 cell cycle progression (1,2). p70 S6 kinase phosphorylates the S6 protein of the 40S ribosomal subunit and is involved in translational control of 5' oligopyrimidine tract mRNAs (1). Important S6 ribosomal protein phosphorylation sites include several residues (Ser235, Ser236, Ser240, Ser244) located wtihin a small, carboxy-terminal region of the S6 protein (3,4). p70 S6 kinase has been shown to phosphorylate eIF4B at the rapamycin-sensitive site Ser422 in vivo, and a Ser422Ala mutant of eIF4B shows diminished activity in an in vitro translation assay (5). Phosphorylation of eEF2K by p70 S6 kinase and p90RSK leads to inactivation of eEF2K (6), facilitating the dephosphorylation of eEF2 and thus promoting translation.