PLCγ2^−/− mice permit 4T1 allogeneic tumor growth. 5 × 10⁶ 4T1 mammary tumor cells were s.c. injected in PLCγ2^−/− or WT mice and tumor growth was evaluated for 14 d. Percentage of MDSCs in spleen was then analyzed by FACS using anti–Gr-1 and CD11b staining. Results represent mean ± SD (n = 3). One representative experiment of two is shown. *, P < 0.05; **, P < 0.01; ***, P < 0.001.