Pak2-deficient MDSCs are more suppressive than MDSCs from tumor-bearing mice. Mice reconstituted with WT and Pak2-KO BM were inoculated with LLC cells or PBS control subcutaneously. (A) The numbers of CD45.2⁺CD11b⁺Gr1^high (representing PMNs and MDSCs) and CD45.2⁺CD11b⁺Gr1^low cells (representing monocytes) are shown per spleen. (B) Effects of splenic Gr1^highLy6G⁺ cells on T-cell proliferation. Representative data from 2 experiments with 5 to 9 mice per genotype are shown. *P < .05; **P < .01; ***P < .001; ****P < .0001; ns, not significant.