As shown in Figure 1D,E, IFITM2 and IFITM3 were more potent than IFITM1 to suppress infection of CXCR4-tropic viruses NL4.3 and HXB2 in U87.CD4.CXCR4 cells, infection of CCR5-tropic viruses AD8 and JRFL in U87.CD4.CCR5 cells, as well as infection of the dual tropic HIV-1 89.6 in both U87.CD4.CXCR4 and U87.CD4.CCR5 cells, regardless their co-receptor usages. This evidence concerns the gene CXCR4 and infection.