Since the higher levels of Hsp70 are associated with drug resistance to Hsp90 inhibitors (11,26,27), the effect of X-ray irradiation on Hsp70 levels may be another mechanism, in addition to the effect of NVP-BEP800 on the NF-κB signaling pathway, for the action of the combined treatment on glioblastoma cells. The gene discussed is NFKB1; the disease is glioblastoma.