Sur-TCR-Tg T-ALL overexpress Notch1 and cell lines are sensitive to treatment with NOTCH inhibitors and/or cyclosporine A. (A) Immunofluorescent staining of anti-NOTCH1 antibodies in thymi of 1 representative preleukemic (left) and leukemic (right) Sur-TCR-Tg mouse (×50 magnification). Similar results were observed in >4 animals. (B) Three separate Sur-TCR-Tg T-ALL lines were treated with a GSI or CsA or both agents and live cells were counted daily during a 1-week culture. Stars designate cultures where significantly reduced cell counts were observed F8-3 and L8-2 using either GSI or CsA or the combination. Results are representative of 4 independent experiments for each cell line.