ACHE and neoplasm: Targeting muscarinic acetylcholine receptor 3 (M3R) through selective and non-selective antagonists (p-fluorohexahydro-sila-difenidol hydrochloride and atropine respectively) repressed H508 colon cancer cell proliferation by approximately 40% whilst acetylcholinesterase inhibitors were capable of stimulating tumor growth by 2 to 2.5 fold (Cheng et al., 2008), indicating participation of cholinergic signaling in tumor development.