To determine if THC was exerting effects on medulloblastoma and ependymoma cells via the activation of CB1R, cells were pre-incubated with the CB1R-selective antagonist SR141716 (SR1) followed by incubation with a sub-effective dose of THC, and cell viability was assessed using alamar blue assay after 72 h. This evidence concerns the gene CNR1 and medulloblastoma.