Protopine, an isoquinoline alkaloid contained in plants in northeast Asia. IC50 Value: Target: In vitro: Protopine was found to reduce nitric oxide (NO), cyclooxygenase-2 (COX-2), and prostaglandin E(2) (PGE(2)) production by LPS-stimulated Raw 264.7 cells, without a cytotoxic effect. Pre-treatment of Raw 264.7 cells with protopine reduced the production of pro-inflammatory cytokines [2]. Protopine is a novel microtubule stabilizer with anticancer activity in HRPC cells through apoptotic pathway by modulating Cdk1 activity and Bcl-2 family of proteins [3]. In HepG2 cells, protopine significantly increased CYP1A1 mRNA levels after 24h exposure at concentrations from 25 and 10 μM. Protopine also dose-dependently increased CYP1A1 and CYP1A2 mRNA levels in human hepatocytes [4]. In vivo: Assays were performed on MDA-MB-231 human breast cancer cells, and the result showed that protopine exhibited anti-adhesive and anti-invasion effects in MDA-MB-231 cells; after treatment with protopine for 90 min, the expression of EGFR, ICAM-1, αv-integrin, β1-integrin and β5-integrin were remarkably reduced [1].