GPR55 and central nervous system cancer: In glioblastoma (GBM), the highest-grade IV glioma, members of the large membrane receptor family of G protein-coupled receptors (GPCRs) are upregulated including CB1 and GPR55 that along with non-selective ion transporter protein TRPV1 bind endocannabinoids and phytocannabinoids with different affinities and signalling effects.