Overview:

p70S6K is responsible for the phosphorylation of 40Sribosomal protein S6, and is ubiquitously expressed inhuman adult tissues (1). p70S6K is activated by serumstimulation and this activation is inhibited by wortmanninand rapamycin. p70S6k activity changes during the cellcycle, and increases 20-fold in G1 cells released from G0(2). p70S6K activation requires sequential phosphorylationat proline-directed residues in the putative autoinhibitorypseudosubstrate domain, as well as threonine 389, a sitephosphorylated by phosphoinositide-dependent kinase 1(PDK-1).

References:

1. Ferrari, S. et al: S6 phosphorylation and the p70s6k/p85s6k.Crit Rev Biochem Mol Biol. 1994;29(6):385-413. Review.2. Edelmann, HM. Et al: Cell cycle regulation of p70 S6 kinaseand p42/p44 mitogen-activated protein kinases in Swissmouse 3T3 fibroblasts. J Biol Chem. 1996 Jan 12;271(2):963-71.