The pathological states of neurological disorders and neurodegenerative diseases, including AD, amyotrophic lateral sclerosis, Niemann-Pick type C disease, and ischemic stroke, lead to cleavage of p35 into the more stable p25 by the calcium-dependent protease calpain and to increased CDK5 activity22. The gene discussed is CDK5; the disease is amyotrophic lateral sclerosis.