Strong evidence supports the latter claim—M1R deficiency in murine colon cancer models augments colon neoplasia [12], increasing concentrations of M1R agonists progressively reduce human colon cancer cell proliferation [13], and, compared to adjacent normal colon, M1R/CHRM1 expression is significantly reduced in human colon cancers [14]. This evidence concerns the gene CHRM1 and malignant colon neoplasm.