CXCR4 and infection: Previous studies have suggested that the inhibition of productive infection with HIV-1 by Prostratin was mediated by the down-regulation of HIV-1 receptors CD4, CCR5 and CXCR4 (Biancotto et al., 2004; Kulkosky et al., 2001; Rullas et al., 2004; Warrilow et al., 2006).