In order to determine whether viral oncoproteins actively contribute to the elevated sensitivity of HPV-infected cells to radiation therapy, immortalized keratinocytes (HaCaT) and three cancer cell lines (A431, UPCI-SCC-111 and U-2OS) from different origins and displaying different TP53 mutation statuses were transduced with HPV16 E6 and/or E7 (Figure 2A). Here, TP53 is linked to cancer.