Rsk3

Rsk3 belongs to the p90 ribosomal S6 kinase (Rsk) family of serine/threonine protein kinases. Other Rsk family members, such as Rsk1 and Rsk2, have been shown to mediate cell survival, motility and proliferation. Despite being originally identified more than 10 years ago, little is known about the biological function of Rsk3 and its isoform-specific role within the Rsk family. The use of specific Rsk inhibitors and RNA interference should help shed light on the role and contribution of this Rsk family member. Rsk3 has been suggested to play roles during cell cycle progression based on several findings. First, Rsk3 was shown to translocate to the nucleus of serum-stimulated HeLa cells, coincident with G0/G1 cell cycle transition. Although these findings were never demonstrated in vivo, Rsk3 was found to phosphorylate c-Fos and histones in vitro. More recently, Rsk3 was suggested to behave as a tumor suppressor as it was found to be mutated in ovarian cancer, suggesting that Rsk3 may in fact inhibit cell cycle progression.