These data, together with previous findings by Lo Dico et al. (13) showing that a significant reduction in HIF-1α activity precedes a response to TMZ treatment in GBM cells, led us to explore this activity further, and we found that changes in HIF-1α activity correlate with TMZ-induced changes in the viability of TMZ-sensitive and TMZ-resistant cells under both normoxic and hypoxic conditions. Here, HIF1A is linked to glioblastoma.