PTX blocks gp120-induced MAPK phosphorylation in TCR-engaged primary T cells.

CD4⁺ lymphocytes were prestimulated with immobilized αCD3 and αCD28 mAbs for 3 days, followed by a 16-hour culture in the presence of PTX (100 ng/mL) or a 20-minute culture in the presence of EGTA (2 mM). Nontreated, PTX-treated, and EGTA-treated cells were then either stimulated with gp120, SDF-1, an αCD3 mAb, or an αCD4 mAb, as indicated. Membranes immunoblotted with a pAb recognizing the dually phosphorylated Erk1/Erk2 are shown.