The observed enhancement of R5 HIV-1 entry by CXCL14 was dependent on CXCR4, as infection of CXCR4-deficient GHOST cells that were engineered to coexpress CD4 and CCR5 by R5 HIV-1 was not affected by CXCL14 (Fig. 7D). This evidence concerns the gene CXCR4 and infection.