Since normal tissue samples were derived from full thickness colon tissue samples and M2 and M4 muscarinic receptor subtypes are predominantly localized in intestinal smooth muscle, we were not surprised to observe reduced CHRM2 and CHRM4 expression levels in samples of adenocarcinomas which derive from intestinal epithelial cells; in fact, these findings provided an internal validation of our methodology. The gene discussed is CHRM4; the disease is adenocarcinoma.