RPA1 and head and neck cancer: Given the upregulation of γH2AX (Figures 1B and 1C, 3 and 4) and formation of RPA foci (Figure 4) after roscovitine treatment in HPV+, but not in HPV-, head and neck cancer cells, we sought to examine whether roscovitine did truly selectively induce DNA damage in HPV+ cells.