Down-regulation of β-catenin regulates MDSC accumulation and tumor growth. (A) Western blot analysis displaying expression levels of PLCγ2, β-catenin, p-PKC and p-GSK3β in MDSCs isolated from tumor-bearing WT and PLCγ2^−/− mice. β-actin was used as loading control. One representative blot out of 3 independent experiments is shown. (B) Western blot analysis displaying expression levels of PLCγ2 and β-catenin in PLCγ2^−/− MDSCs stimulated with PDBu or saline for 18 h. β-actin was used as loading control. One representative blot out of two independent experiments is shown. (C) 10⁵ LLC cells were s.c. injected in β-cat.cKO or control mice (CTR) and tumor growth followed for 14 d. BM, spleen and tumors were then analyzed by FACS using anti–Gr-1 and CD11b staining to measure the percentage of MDSCs. Mean ± SD (n = 8) are shown. One representative out of 3 independent experiments is shown. *, P < 0.05, **, P < 0.01, ***, P < 0.001. (D) WT mice s.c. inoculated with LLC cells were adoptively transferred on days 3 and 6 with 3 × 10⁶ CTR- or β-cat.cKO-MDSCs isolated from LLC tumor–bearing mice. Saline injection was used as control. Tumor growth was followed for 14 d. The percentage of MDSCs was determined by FACS in spleen 14 d after tumor inoculation. Mean ± SD (n = 6) are shown. Data are reported from one of two similar independent experiments. **, P < 0.01.