Lyn kinase activation is CCR5-dependent. MDMs were harvested from donors homozygous for either the CCR5 wild-type (WT) or Δ32 deletion (CCR5Δ32) alleles, pretreated for 1 hour with or without the Src inhibitor PP2 (10 μM), and stimulated for 1 minute with R5 gp120 (40 nM) or MIP-1β (25 nM). Cell lysates were then either immunoprecipitated using anti-Lyn antibodies followed by in vitro kinase assay (KA; top row), or analyzed for total Lyn protein by Western blot (WB; bottom row).