Figure EV1. Prazosin induces GIC apoptosis.

1. Flow cytometry analysis for CD15, Annexin V and DAPI in prazosin‐treated GBM44 cells. Prazosin induces apoptosis in both CD15⁺ and CD15⁻ glioblastoma cells.
2. TUNEL staining shows increased numbers of tumor cells undergoing apoptosis following in vivo prazosin treatment of GBM44‐bearing mice. Right panel: quantification of TUNEL‐positive glioblastoma cells in vehicle‐ versus prazosin‐treated mice. Protocol design is schematized in Fig 2A. Mice were sacrificed 48 h after the last prazosin injection. Scale bar: 50 μm. Results are presented as mean ± SD in biological quadruplicates from three independent experiments. *P < 0.05, two‐sided Mann–Whitney U‐test.
3. In vivo prazosin treatment does not alter angiogenesis. Representative H&E images of tumors initiated with GBM44 grafting. Mice were treated according to the protocol depicted in Fig 2A and sacrificed 2 days after the last prazosin injection. Arrowheads point to blood vessels. Scale bar: 50 μm.
4. Viability analysis of GICs that escaped prazosin treatment. GICs having escaped a first prazosin treatment are responsive to a second prazosin treatment at 30 µM. GICs were treated with prazosin for 72 h. The medium was then replaced with fresh medium, and the cells were allowed to recover for 2 weeks prior to be exposed to prazosin for 72 h.