CNR1 and colorectal cancer: Cannabinoids have been shown to interact with sonic hedgehog [20], fibroblast growth factor ((FGF) [115, 116], including transactivation of the FGF1R by CB1R [117]; bone morphogenetic proteins [118–120], retinoic acid signalling [121–123], notch signalling [124–128] (which is very involved in colorectal cancer), Wnt signalling [129–134] and the hippo pathway [64].