To elucidate the role of FOSL1 in response to TMZ, a DNA alkylating drug that induces cell cycle arrest in GBM cells, we analyzed the levels of FOSL1 and G0/G1 to S phase transition‐associated proteins, including CDK2, CDK4, cyclin D, and cyclin E29, in primary GBM cells with unmethylated (TMZ‐resistant group) or methylated MGMT (TMZ non‐resistant group). This evidence concerns the gene CDK2 and glioblastoma.