To test this hypothesis in in vitro experiments, we selected two GBM cell lines (A172 and T98G) which were reported to have similarly high GPR81 expression but distinct MGMT methylation and expression status in GSE6837928; specifically A172 was characteristic of high methylation and low expression of MGMT, while T98G was characteristic of low methylation and high expression of MGMT (Figure 7I and Figure S2). This evidence concerns the gene HCAR1 and glioblastoma.