Effect of silencing the γ-catenin expression by RNA interference on the phenotype of Sca1⁺/lin^- HSCs expressing AATPs. (A) Effect of siRNA constructs on Phoenix cells overexpressing γ-catenin. Two different siRNA constructs (siRNA-9 and siRNA25) were cotransfected into Phoenix cells together with the PINCO-γ-catenin. Thirty-six hours after transfection whole cell lysates were probed with an anti-γ-catenin antibody in Western blot analysis. Equal protein loading was confirmed after stripping of the membrane and staining with an anti-β-tubulin antibody. (B) Effect of siRNA-25 on cell cycle progression of HSCs expressing X-RARα. An siRNA directed against the β-galactosidase (siRNA-LacZ), which had no effect on γ-catenin expression (data not shown), was used as control. (C) Effect of siRNA-25 on the replating efficiency of Sca1+/lin- HSCs expressing AATPs. The siRNA-LacZ was used as control (Roman numerals indicate the number of the plating round). Original magnification, × 25. (D) Effect of siRNA-25 on the differentiation block induced by AATPs. The siRNA-LacZ was used as control. Gr-1 and Mac-1 were detected as markers of myeloid differentiation and Sca1 and c-kit were detected as stem cell markers.