In addition to these intrinsic resistance mechanisms, GBM cells employ efflux pumps, such as the ATP‐binding cassette transporters, to actively expel chemotherapeutic agents, thereby reducing their intracellular concentration and effectiveness.[95, 96] GBM's highly heterogeneous nature further complicates treatment, as different cell populations within the tumor may respond differently to therapies. This evidence concerns the gene ABCA4 and glioblastoma.