Ribosomal protein S6 kinase <p>This entry represents ribosomal protein S6 kinase. S6 kinase is part of the mammalian target of rapamycin (mTOR) pathway, which is a key regulator of cell growth via the regulation of protein synthesis. Both S6 kinase and eukaryotic initiation factor 4E-binding protein 1 (4EBP-1) are key mTOR effectors of cell growth [<cite idref="PUB00042699"/>]. S6 kinase specifically phosphorylates ribosomal protein S6 in response to insulin or several classes of mitogens. S6 kinase is activated by serine/threonine phosphorylation and protein kinase C, and is inactivated by type 2A phosphatase [<cite idref="PUB00042700"/>]. S6 kinase interacts with PPP1R9A/neurabin-1 [<cite idref="PUB00042701"/>].</p>