CXCR4 and HIV-1 infection: It was reported that FPRL1 activated by the fMLF peptide or peptides derived from the Env glycoprotein gp120 of HIV-1 interferes with the coreceptor function of CCR5 and CXCR4 by down-regulating them, and as a result, these peptides prevent HIV-1 infection [32,42,43].