H2AX and head and neck cancer: In addition, analogous to the results obtained with HPV- SCC61 cells, 24 hour treatment with roscovitine downregulated phosphorylation of H2AX in two other HPV-negative head and neck cancer cells, SCC35 and Fadu, with γH2AX levels restored back to control untreated cells 48 hours after the treatment (Figure 1D).