Ataxia telangiectasia mutated (ATM) is a Ser/Thr protein kinase which activates checkpoint signaling upon double strand breaks, apoptosis and genotoxic stresses such as ionizing ultraviolet A light, thereby acting as a DNA damage sensor. ATM is also involved in signal transduction and cell cycle control and may function as a tumor suppressor. Defects in ATM are the cause of ataxia telangiectasia, leukemia, and lymphoma.The synthetic peptide used to raise the antibody Cat. No. 200158 is selected from a sequence within the center region of human ATM. For blocking experiments, a 10 to 100 fold molar excess to antibody is recommended.