Engagement of σ-1 receptor (σ-1R) is critical for cocaine-induced PDGF-BB expression. (A) Pretreatment of HBMECs with σ-1R antagonist BD1047 or progesterone inhibited cocaine-induced induction of Egr-1. (B) σ-1R siRNA but not nonspecific siRNA inhibited cocaine-mediated induction of Egr-1 expression. (C) Pretreatment of HBMECs with σ-1R antagonist BD1047 or progesterone inhibited cocaine-mediated induction of PDGF-BB expression. (D) σ-1R siRNA, but not nonspecific siRNA inhibited cocaine-mediated induction of PDGF-BB. All the data are presented as mean ± SD of 4 separate experiments. **P < .01 vs control group; #P < .05, ##P < .01 vs cocaine-treated group.