– Serine / threonine-protein kinase SRPK3, also known as Muscle-specific serine kinase 1, Serine/arginine-rich protein-specific kinase 3, SR-protein-specific kinase 3, Serine / threonine-protein kinase 23, MSSK-1, SRPK3 and MSSK1, is a member of the protein kinase superfamily and CMGC Ser / Thr protein kinase family. SRPK3 is a protein kinase belonging to serine/arginine protein kinases (SRPK) family, which phosphorylates serine / arginine repeat-containing proteins, and is controlled by a muscle-specific enhancer directly regulated by MEF2. SRPK3 / MSSK1 contains one protein kinase domain. SRPK3 / MSSK1 is exclusively expressed in skeletal and heart muscle. It is required for normal muscle development. Myocyte enhancer factor 2 (MEF2) plays essential roles in transcriptional control of muscle development. Normal muscle growth and homeostasis require MEF2-dependent signaling by SRPK3.