RSK4 also known as ribosomal protein S6 kinase polypeptide 6 is encoded by the RPS6KA6 gene. RSK4 is a member of the RSK (ribosomal S6 kinase) family of serine and threonine kinases and may be distinct from other members of this family. As studies suggest it is not growth factor dependent and may not participate in the same signaling pathways.