During the p.i. phase GBM cells underwent extensive phenotypic changes characterized by upregulation of senescence and stemness markers, and overexpression of both the proapoptotic Bax and the antiapoptotic Bcl-2 gene, a likely indication of radiation-stimulated apoptosis on one hand, and of the apoptosis-refractory phenotype of the radiation-resistant cells on the other. This evidence concerns the gene BCL2 and glioblastoma.