CXCR4 and HIV-1 infection: GNB3 825T allele carriers demonstrate increased SDF-1α-mediated lymphocyte chemotaxis [18] (a process mediated by G protein signaling); therefore, we wondered whether CXCR4 ligand SDF-1α or CCR5 ligand MIP-1β would be differently expressed between GNB3 genotypes, particularly during HIV-1 infection.