Phosphorylates PPP1C, phosphorylase b and CFTR. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with PPP1C and inhibitor-2. Mainly expressed in skeletal muscle, and weakly in brain and pancreas. Autophosphorylated. Phosphorylated (By similarity). Belongs to the protein kinase superfamily. Tyr protein kinase family. LMTK2 entry