TP53 and infection: There was no noticeable increase of S and G2 phase cells in both HCT116 p53+/+ and HCT116 p53−/− cells 4 h and 8 h post infection, but significant increases in S and G2 phase cells were found in both HCT116 p53+/+ cells and HCT116 p53−/− cells 16 h post infection (Fig. 4).