CNR1 and cancer: Cannabidiol (CBD) is a non-toxic and non-psychoactive cannabinoid that has been shown to have antitumor activity in multiple cancer types.11 Activation of CB1 and CB2 receptors has been previously shown to lead to the inhibition of tumor progression;12 however, CBD does not interact efficiently with CB1 and CB2 receptors, and the initial site CBD interacts with to produce antitumor activity is unknown.