ATM and ataxia telangiectasia: Several other studies, however, also support that knockdown of ATM causes expression of S phase markers in post-mitotic neurons [58, 80, 103, 104] and enhance apoptosis [58, 80, 104], which both seem to increase under conditions of oxidative stress [104], confirming the neurodegenerative phenotype and susceptibility to cancer [68] seen in AT patients.