CDKN1A and HIV-1 infection: In a related experiment in undifferentiated and transdifferentiated BlaER1 cells, transient induction of p53 was observed 24 h after HIV-1 infection in the presence and absence of VPX, which correlated significantly with p21 induction with high expression in the presence of VPX from HIV-2, which degrades SAMHD1 (87, –, 90) (Fig. 6C).