ATM and cancer: During the proliferation, arrestcells are relatively protected from DNA damaging chemotherapy (e.g. CDDP).19 In cancercells, serum starvation additionally activates the ATM/Chk2/p53 stress responsesignaling pathway.19 This hyperactivation of the ATM/Chk2/p53 pathway results inoverloading stress which is thought to exhaust cellular stress response andsensitizes cancer cells to DNA damaging chemotherapy.19