Nle is required for pre-60S export in HSCs/MPPs but not in B cells. (A) Its2 labeling in hematopoietic cells. At day 3, control and Nle^cKO hematopoietic cells were stained with c-Kit antibody and its2 probe (left). CD19-control and CD19-Nle^KO cells from BM and spleen were stained with IgM antibody and its2 probe (right). Bar, 5 µm. (B) Representative histograms for its2 and its1 labeling in SLAM cells, immature progenitors (Lin⁻ Sca-1⁺ CD150⁺ CD48⁺ or Lin⁻ Sca-1⁻ c-Kit⁺), and Lin⁺ cells at day 3 or 5 after Cre induction from control and Nle^cKO mice. Three independent FACS experiments showed similar results. (C) Quantification of its2/its1 intensity and RNA level ratios in populations from control and Nle^cKO mice measured at day 3 by FISH (left) or RT-QPCR (right). Bars are means (SD) of n = 3–4 mice per genotype. Data are from one representative of two experiments. *, P < 0.05. (D) Representative histograms for its2 labeling by FISH in BM pre-B and immature B cells and splenic B cells from CD19-control and CD19-Nle^KO mice. (E) Quantification of its2/its1 intensity ratio in B cell populations from CD19-control and CD19-Nle^KO mice. Bars are means (SD) of n = 3 mice per genotype from one experiment.