Activation of ATM is triggered by DNA double-strand breaks (DSBs), oxidative damage, and alterations in chromatin structure, while RPA-bound single-stranded DNA activates ATR. Prior studies had shown that SV40 can replicate in the absence of functional ATM or ATR, but the result is a reduction in unit-length viral DNA. The Fanning lab???s goal was to understand how this occurs, and to determine th