GP1a inhibits Mmp9 expression induced by CCP in myeloid immune cells. (A) BMMΦs, BMDCs, or primary microglia were treated with CCP with or without CB2R agonists GP1a (5μM) or O-1966 (5μM) for 24 hours. RNA was extracted and subjected to qRT-PCR for Mmp9. N.D. indicates not determined. (B) BMDCs were treated with CCP with or without GP1a (5μM), and RNA was extracted at different time points and subjected to qRT-PCR for Mmp9. (C) BMDCs were treated as described in panel B, and supernatants collected at various time points were subjected to MMP-9 ELISA. (D) BMDCs were treated with different concentrations of GP1a for 48 hours, and the resulting supernatants were subjected to MMP-9 ELISA. Data in panels A and B are normalized to housekeeping gene β-actin and presented as fold change compared with untreated samples. *P < .05, **P < .01, *** P < .001 compared with CCP. Data are representative of 2 (A-B) and 4 (C-D) independent experiments.