Acts as a positive regulator of ERK phosphorylation downstream of fibroblast growth factor-receptor activation. Involved in the regulation of both caspase-dependent apoptosis and caspase-independent cell death. In the skin, it plays a predominant role in suppressing caspase-dependent apoptosis in response to UV stress in a range of dermal cell types. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Detected in basolateral and apical membranes of all tubular epithelia. Detected at apical cell-cell junctions. Colocalized with FGF receptors to the cell membrane. Expressed in brain, heart, skeletal muscle, kidney and lung. Expressed in maturing tubular epithelia, with the most prominent expression in the medulla and the papilla. Expressed in thin ascending limb of the loop of Henle and the distal convoluted tubule. Expressed in all layers of transitional ureteric epithelium and in the ureteric smooth-muscle cells (at protein level). Widely expressed. Highly expressed in many brain regions, including in cerebellum, olfactory, hippocampus and cerebral cortex. At 14.5 dpc detected in lung and skeletal muscle, and by 18.5 dpc detected in skin, whisker, gut and testis. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.