To investigate the role of PKM2 in cancer cell resistance to DNA-damaging therapies, we stably knocked down PKM2 in the human glioblastoma multiforme (GBM) U87 cell line, which expresses high endogenous levels of PKM29 (Supplementary information, Fig. S1a), and subjected these cells to ionizing radiation (IR). The gene discussed is PKM; the disease is glioblastoma.