We have previously found that EBV induces rapid proliferation such that at approximately 3 days post infection the first three to four cell divisions occur within a 24-h period.21 The majority of infected cells that begin this hyper-proliferation program ultimately succumb to an ATM/Chk2-dependent senescence-like growth arrest.21, 38 In this study, we sought to determine the upstream molecular source of the DDR. Here, CHEK2 is linked to infection.