Whereas, this interesting finding requires further study, differences in the reactivity of MGMThigh T98G, and MGMTlow U87 cells to TMZ, in particular the inhibition of U87 invasiveness after Cx43 up-regulation (as compared to the opposite effect in T98G populations), suggests that MGMT is a prerequisite for Cx43-dependent/TMZ-induced microevolution of invasive GBM lineages. This evidence concerns the gene GJA1 and glioblastoma.