GFP expression and HA epitope levels in adult Meis1^em1Bcca/Meis1^wtmouse BM correspond to endogenous Meis1 expression. (A) Flow cytometric analysis indicates higher GFP expression level and percentage in more immature cell fractions (Lin⁻Sca-1⁺c-Kit⁺ [LSK] > Lin⁻Sca-1⁻c-Kit⁺ [LK] > Lin⁻Sca-1⁺c-Kit⁻ [LS], Lin⁻Sca-1⁻c-Kit⁻ [L]). (B) Differential GFP intensity of LSK, LK, LS, and L cell fractions is observed through fluorescence microscopy with a ×100 original magnification. (C) Meis1 mRNA levels (Ex7-8) in LSK, LK, LS, and L cell fractions are similar in both the WT control mice and the heterozygous (Meis1^em1Bcca/Meis1^wt) mice (n = 3). (D) Dynamic changes in Meis1 mRNA expression are reflected in the GFP level and percentage during in vitro culture. (E) Flow cytometric analysis for HA epitope expression at day 8 of in vitro–cultured LSK cells from adult mouse BM with intracellular staining (with anti-HA antibody) indicates a strong positive correlation between HA and GFP expression level.