GPR133 activates Gαs and adenylyl cyclase in vitro, leading to cAMP elevation.36 To test whether GPR133 signaling in GBM is also mediated by cAMP, we used an activator of adenylyl cyclase, forskolin (10 μM), to rescue effects of GPR133-KD no. 1. This evidence concerns the gene ADGRD1 and glioblastoma.