ERK-1/2 activation through CCR5 is sensitive to Src inhibition. MDMs were pretreated for 1 hour with the Src kinase inhibitor PP2 (10 μM) or the negative control PP3 (10 μM), then stimulated for 15 minutes in the continued presence of the inhibitor with (A) R5 gp120 (40 nM) or (B) MIP-1β (25 nM). Cell lysates were subjected to ERK-1/2 Western blot using phospho-specific (P-ERK) or total ERK-1/2 antibodies (T-ERK).