Ribosomal Protein S6 Kinases (RSK)

The 90 kDa ribosomal protein S6 kinases (RSK1-4) are a family of broadly expressed Ser/Thr kinases activated in response to mitogenic stimuli, including growth factors and tumor-promoting phorbol esters. RSKs are directly phosphorylated by ERK1 and ERK2, leading to RSK autophosphorylation and activation. Active RSKs appear to play a major role in transcriptional regulation by translocating to the nucleus and phosphorylating c-Fos and CREB.