Normal hematopoiesis in the combined absence of β- and γ-catenin. (A) Experimental strategy: CD45.2⁺ FL cells (E12.5-E14.5) from γ-catenin^−/− β-catenin^lox/lox (control) and γ-catenin^−/− β-catenin^{lox/lox,Mx-Cre} (β/γ dko) embryos were isolated and transplanted into lethally irradiated congenic wt mice (CD45.1⁺). At 8 weeks after reconstitution, all mice were injected 5 times at 2-day intervals with pI-pC to inactivate the floxed β-catenin alleles via induction of the Mx-Cre transgene. Mice were analyzed 5 to 7 weeks after the last pI-pC injection, and a fraction of T cell–depleted BM cells derived from these FL chimeras were used to set up mixed BM chimeras and serial transplantations, which were both analyzed between 6 weeks and 6 months after transplantation. B. (Left) Western blot analysis performed on embryos from either wt (control) or γ-catenin^−/− mice showing the absence of γ-catenin protein in the conventional γ-catenin knock-out embryos. Tubulin was used as a loading control. (Right) Southern blot analysis of EcoRI-digested genomic DNA derived from sorted CD45.2⁺ BM cells from 2 control and 2 β/γ dko chimeras 7 weeks after inactivation of the floxed β-catenin alleles are shown. Floxed indicates the floxed β-catenin alleles, and deleted indicates the inactivated alleles (98%-100%). (C) Absolute numbers of either total or CD45.2⁺ BM cells derived from control (n = 7; □) and β/γ dko (n = 8; ■) chimeras. (D) Representative FACS analysis of KLS HSCs defined by CD117 and Sca1 after gating on Lin⁻ BM (top row) and by CD135 and CD34 after gating on KLS (bottom) BM cells derived from control and β/γ dko chimeras. (E) Absolute numbers of KLS HSCs (CD117⁺Lin⁻Sca1⁺), LT-HSCs (CD117⁺Sca1⁺CD34⁻CD135⁻), ST-HSCs (CD117⁺Sca1⁺CD34⁺CD135⁻), MPPs (CD117⁺Sca1⁺CD34⁺CD135⁺), and CMPs (CD117⁺Sca⁻) gated on Lin⁻ CD45.2⁺ BM cells derived from control (n = 7; □) and β/γ dko (n = 8; ■) chimeras. The error bars represent mean (± SD) in panels C and E.