RCP168 is a highly selective and affinity CXCR4 receptor antagonist ( IC 50 =5 nM). RCP168 has a stronger ability than natural chemical factors to inhibit the entry of HIV-1 (human immunodeficiency virus type 1) into host cells via CXCR4 receptors. RCP168 inhibits HIV-1 infection by blocking viral binding sites or inducing receptor internalization. RCP168 can be used to analyze the interaction between CXCR4 receptor and other chemical factor receptors.