(A) 22Rv1 and (B) PC-3 cells were were plated in invasion chambers and were treated with nicotine. (C) 22Rv1 cells were treated with nicotine, hepatocyte growth factor (HGF), or both, to assess whether nicotine and HGF have a synergistic effect on matrigel invasion. (D) Nicotinic acetylcholine receptor antagonist, mecamylamine (MCA), significantly decreased nicotine-induced increase in matrigel invasion, but not HGF-induced increase in invasion, in 22Rv1 cells. Shown are mean ± SD for n = 3. *Significantly different from control (P < 0.05).