This gene encodes a member of the RSK (ribosomal S6 kinase) family of serine/threonine kinases. This kinase contains 2 nonidentical kinase catalytic domains and phosphorylates the S6 ribosomal protein and eucaryotic translation initiation factor 4B (eIF4B). Phosphorylation of S6 leads to an increase in protein synthesis and cell proliferation.