MMP1 and malignant colon neoplasm: Xie et al. showed that activating human colon cancer cell muscarinic receptors with ACh selectively induced expression of MMP 1, 7, and 10 [93], and Raufman et al. showed that treating CRC cells with atropine to block M3R activation or with a neutralizing anti-MMP1 antibody abolished ACh-induced cell invasion [83].