Asxl1 is ubiquitously expressed in hematopoietic cells. Southern blot analysis of Asxl1, Bmi1, and actin gene expression in total amplified cDNAs from FACS-sorted hematopoietic cell populations from fetal liver and adult bone marrow, spleen, and thymus. Total cDNAs were amplified using RT-PCR from 10⁴ sorted cells, and each sample with or without reverse transcriptase (RT + or −) was sequentially hybridized to each probe. Results for a representative experiment are shown; duplicate experiments were performed. (A) Asxl1 is expressed in unfractionated E14.5 fetal liver (TFL), and the hematopoietic stem cell–depleted (Sca-1⁻Lin⁺ [S⁻L⁺]), low (Sca-1⁺Lin⁺ [S⁺L⁺]), and enriched (Sca-1⁺Lin⁻ [S⁺L⁻]) subpopulations, whereas Bmi1 expression is predominant in the 2 Sca-1⁺ fractions. (B) Asxl1 is expressed in unfractionated adult bone marrow (TBM) and in all fractionated adult bone marrow, spleen, and thymus cells investigated, whereas Bmi1 is expressed predominantly within the progenitor-enriched Sca-1⁺ fractions and the Gr-1 low fraction of total bone marrow, with very low or undetectable expression in other fractions.