MAP / microtubule affinity-regulating kinase 3, also known as C-TAK1, cTAK1, Cdc25C-associated protein kinase 1, ELKL motif kinase 2, Protein kinase STK1, Ser/Thr protein kinase PAR-1, Serine/threonine-protein kinase p78, MARK3, CTAK1 and EMK2, is a ubiquitous expressed protein which belongs to theprotein kinase superfamily, CAMK Ser / Thr protein kinase family and MARK subfamily. MARK3 contains oneKA1 (kinase-associated) domain, oneprotein kinase domain and oneUBA domain. The Par-1 / MARK protein kinases play a pivotal role in establishing cellular polarity. This family of kinases contains a unique domain architecture, in which a ubiquitin-associated (UBA) domain is located C-terminal to the kinase domain.MARKs / PAR-1 are common regulators of cell polarity that are conserved from nematode to human. All of these kinases have a highly conserved C-terminal domain, which is termed the kinase-associated domain 1 (KA1).