RSK2 and its binding partners in cell proliferation, transformation and cancer development.

RSK2 is a serine/threonine kinase and a member of the p90 ribosomal S6 kinase (p90(RSK); RSKs) family, which regulates cell proliferation and transformation induced by tumor promoters such as epithelial growth factor (EGF), 12-O-tetradecanoylphorbol-13-acetate (TPA), and ultraviolet (UV) radiation. RSKs respond to many growth factors, hormones, neurotransmitters and environmental stresses. In signaling cascades, RSK2 is regulated under the control of extracellular signal-regulated kinase 1 (ERK1) and 2 (ERK2) activities and is positioned upstream of transcription and epigenetic factors involved in cell proliferation, cell transformation and cancer development, as well as some kinases that modulate cell cycle progression. Over the last decade, our research group has studied the etiological roles of RSK2 in human cancer development, discovering that RSK2 plays a key role in cell proliferation, transformation and cancer development in humans. Based on our research, we concluded that RSK2 plays a key role as an onco-kinase by combinational protein-protein interaction with different binding partners depending on the cellular context. In this review, we discuss the function of the RSK2 signaling axis by interactions with binding partners in cancer development.