Indeed, the classic plant-derived cannabinoid delta-9-tetrahydrocannabinol (∆9-THC) acts as a partial agonist at cannabinoid receptors (CB1 and CB2) (Pertwee, 2008), and it was demonstrated to be safe in glioblastoma patients (Guzmán et al., 2006). Here, CNR1 is linked to glioblastoma.