Among the enzymes that have been most convincingly implicated in the pathogenesis of neurodegenerative diseases are protein kinases, a family of about 500 proteins, most of which fall into two types-serine/threonine kinases, which phosphorylate serines and/or threonines in their target protein, and the tyrosine kinases. The gene discussed is MARK2; the disease is neurodegenerative disease.