CNR1 and cancer: Yet, while LPI seems to contribute to cancer progression and metastasis through the activation of GPR55, it was shown in a cholangiocarcinoma model that an endocannabinoid, anandamine (AEA), whose effects were not mediated through the activation of the typical CB1/CB2 receptor or vanilloid 1 receptor, suppressed cholangiocarcinoma growth by inducing apoptosis.