ZMIZ1 promotes murine ETP and immature T-ALL proliferation. (A) Experimental strategy to study dependence of Il7R-GCinsL243/Lmo2-tg-induced immature T-ALL on Zmiz1. Tam = 0.025 mg/g tamoxifen. (B–D) Mice were transplanted with primary Il7R-GCinsL243/Lmo2-tg-induced Rosa26-CreER^T2Zmiz1^f/f immature T-ALL tumors. Representative splenomegaly (white arrow, B), representative Kit/CD25 flow cytometry profiles of secondary tumors within the Lineage⁻CD44⁺ gate (C), and qRT-PCR analysis of ETP-TF5 genes (D) is shown. (E–G) Representative peripheral blood GFP⁺ flow cytometric plots (E), peripheral blood GFP⁺ blast counts (F), and survival (long rank test P value, G) were measured after transplantation of primary tumor per experimental design in A (Experiment #315); n = 3 (control) and 6 (knockout)/group. (H) Schematic of murine T-cell differentiation showing the effect of Zmiz1 deficiency on ETP maintenance. (I–K) Representative thymuses of Vav1-Cre control and Vav1-Cre Zmiz1^f/f mice (scale bar, 2 mm; I); representative Kit/CD25 flow cytometry profiles (J) and subset percentage within the Lineage⁻CD44⁺ gate; n = 6/group (K). Unless otherwise noted, P values were based on a two-sided t test. *P < 0.05; **P < 0.01; ***P < 0.001.