The depletion of Tak1^−/− HSPCs is partially prevented by inactivation of TNF-α signaling. BM of mutant mice was collected on day 8 after induction of Tak1 gene deletion. (A-B) Percentages of phenotypic HSCs (Lin⁻Sca⁺c-Kit⁺) and CPs (Lin⁻Sca⁻c-Kit⁺) in total BM MNCs were analyzed by flow cytometry. BM MNCs were stained with FITC-lineage cocktail, PE-Sca1, and allophycocyanin-c-kit antibodies. HSCs and CPs were analyzed by gating first on the lin^−/lo population (lineage^negative/low); percentages of HSCs and CPs in total BM MNCs were then examined. (C) Absolute numbers of HSCs and CPs were counted. Data are the average of 4 mice from each genotype. **Significant reduction compared with WT control mice (P < .01). #Significant increase compared with Tak1^−/− mice (P < .05). $$Significant increase compared with Tak1^−/Tnfr2^−/− mice (P < .01).