We also verified the increased phosphorylation of H2AX protein at S139 (also called γH2AX) and the increased expression of total FEN1 protein in the two MmuPV1 tumor tissues (samples 1 and 4 in Fig 2B) relative to the two tumor-free tissues (samples 10 and 12 in Fig 2B) (Fig 8C). Here, H2AX is linked to neoplasm.