Killing by armed ATC is resistant to both radiation and temozolomide. TMZ-resistant U251MG cells were used as target cells for overnight killing by unarmed, HER2Bi-, and EGFRBi-armed ATC. The upper panel shows the MTT data and the lower panel shows 51Cr release data. Each panel has three sets of 4 columns. The E:T was 10:1. The individual sets represent the effects of unarmed, HER2Bi-armed, and EGFRBi-armed ATC, respectively. Within each data set, the 4 columns show the viability or cytotoxicity, respectively, for type of treatment with and without irradiation or TMZ (final 100 μM). The four sets of effector cells were untreated (Radiation– TMZ–), irradiated only (Radiation+ TMZ–), exposed to TMZ only (100 μM in the assay medium) (Radiation– TMZ+) and both irradiated and exposed to TMZ (Radiation+ TMZ+). Two assay plates were set up in parallel. The MTT data are shown as mean (± SEM) residual percent viable cells and the mean (± SEM) 51Cr release data as percent cytotoxicity. Two-way ANOVA of the MTT data show highly significant effects of both treatment and arming (p < 0.0001 for each), but no effect of interaction (p = 0.27). For the 51Cr data, treatment (p < 0.0001), arming (p < 0.0001) and the interaction of the two (p = 0.0003) are all highly significant.