Deletion of Zmiz1 inhibits the DN-DP transition. (A-B) Absolute numbers of total thymocytes and DN thymic subsets (A) and representative flow cytometry profiles (B) of LckCre and Zmiz1^ΔLckCre (ΔLckCre) mice. (C) The percentage of CD25^bright cells in the DN3 compartment is indicated as outlined in the black dotted box in panel B. (D-E) Representative flow cytometry profiles (D) and absolute numbers (E) of CD4/CD8 thymic subsets. Mice were between 5 and 8 weeks of age. Horizontal lines indicate means. *P < .05; **P < .01; ***P < .001. Two sample Student t test. DN3a = lineage⁻CD44⁻CD25⁺FSC^loCD27⁻; DN3b = lineage⁻CD44⁻CD25⁺FSC^hiCD27⁺; DN4 = lineage⁻CD44⁻CD25⁻icTCRβ⁺; immature single positive (ISP) = CD8⁺TCRβ⁻. FSC, forward scatter; ns, not significant; SSC, side scatter.