CNR2 and cancer: While our data support the notion that activation of CB2 on immune cells is anti-tumorigenic, others have implicated the expression of CB2 on gut epithelial or endothelial cells, including cross-talk between CB2 and PPARγ (expressed on epithelial cells and macrophages), as well as cross-talk mediated by CB2 between cancer cells and endothelial cells, as a potential mechanism for the pro- or anti-tumorigenic effect [61,62].