CHRM1 and malignant colon neoplasm: As β-catenin is a target of phosphorylation by PKA, which is activated by cAMP (Katoh and Katoh, 2017), reduced expression of CHRM1/M1R in colon cancer would attenuate β-catenin signaling mediated by this non-canonical M1R/cAMP/PKA/β-catenin axis.