The gp120-triggered macrophage TNF-α production depends on Src, ERK-1/2 and CCR5. (A) MDMs from donors homozygous for CCR5 wild-type or Δ32 alleles were maintained in 96-well plates, stimulated with R5 gp120 (40 nM), or LPS (10 ng/mL), and TNF-α levels in supernatant measured 16 hours later by ELISA. (B-D) MDMs from CCR5 wild-type donors were pretreated for 1 hour with the Src inhibitor PP2 or control compound PP3 (each at 10 μM), the ERK-1/2 inhibitors PD98059 or U0196 (each at 10 μM), or the Lyn-specific inhibitory peptide KRX-123.302 (at either 0.1 or 1.0 μM). They were then exposed to R5 gp120 in the continued presence of the inhibitor, and TNF-α levels in supernatant were measured 16 hours later.