GFP level reflects endogenous Meis1 expression. (A) Expression of total BM cells from the Meis1^em1Bcca allele is well correlated with the expression from the WT Meis1^wt allele at the Meis1 locus using RT-qPCR analysis with primers located at exons 7 to 8 (mM_ex7to8), whereas the tagged allele-specific expression detected through the primer set located at the HA epitope to exon 2 (mM_HAtoex2) can be only detected in C57BL/6N-Meis1^em1Bcca mice. (B) Flow cytometric analysis of adult total BM cells from C57BL/6N-Meis1^em1Bcca strain displays a distinct GFP population compared with the cells from WT mice. (C) Sorted GFP⁺ BM cells from heterozygous mice express a higher level whereas GFP⁻ cells express a relatively low level of Meis1 mRNA. (D) Sorted GFP⁺ BM cells from heterozygous mice express a low level of lineage markers while containing a high percentage of the HSC-enriched LSK population. het, heterozygous; homo, homozygous; Lin⁻, lineage-negative.