HCAR1 and glioblastoma: Surprisingly, in in vitro GBM cell experiments, we have revealed the potential MGMT‐dependent impacts of GPR81 on TMZ resistance; specifically in GBM cells with high methylation (or low expression) of MGMT, e.g., A172‐ and MGMT‐silenced T98G cells, GPR81 may enhance TMZ resistance while in GBM cells with low methylation (or high expression) of MGMT, e.g., MGMT‐overexpressed A172 and T98G cells, GPR81 may increase TMZ sensitivity.