TERF1 and glioblastoma: Importantly, in patient‐derived glioblastoma stem cells (h676 GSCs), we found that all the TRF1 inhibitors induced increased global DNA damage as indicated by increased numbers of cells positive for the γH2AX DNA damage marker (Fig 2B); however, in this case owing to the fact that these cells cannot be attached to the plates, we could not perform TIF analysis.