siRNA knockdown of p21 in non-cycling HCT116 p53+/+ cells significantly increased infection of HIV-1 Luc+ virus, and siRNA knockdown of p53 in non-cycling HCT116 p53+/+ cells also increased infection of HIV-1 Luc+ virus but the increase was not statistically significant (Fig. 5e). This evidence concerns the gene CDKN1A and infection.