Enhanced IFN-γ–induced apoptosis in T cells cultured with anti–IGF-1R blocking mAb. Medium, IGF-1 (100 ng/mL), or anti–IGF-1R blocking mAb (10 μg/mL) 48-hour–treated ST4 T cells (0.5 × 10⁶) were cultured for a further 24 hours in the absence or presence of IFN-γ (1000 U/mL). They were then recovered and stained with FITC-conjugated Annexin-V and PI as described in “Materials and methods.” The number of viable, early, or late apoptotic cells was determined by flow cytometric analysis. Lower left region indicates viable cells (Annexin-V^–/PI^–); lower right region, early apoptotic cells (Annexin-V⁺/PI^–); upper left region, necrotic cells (Annexin-V^–/PI⁺); and upper right region, late apoptotic cells (Annexin-V⁺/PI⁺). Percentages of positive cells are indicated. Results of 1 of 3 independently performed representative experiments are shown.