Turnover of tumor-infiltrating MDSC subpopulations in tumor-bearing mice. Tumor-bearing mice were treated with BrdU for various time periods before cell preparation on day 14 of tumor inoculation, and the BrdU uptake by neutrophils and monocytes/monocyte-derived macrophages were analyzed by a flow cytometry. (A) Representative Gr-1 and Ly-6C profiles in CD11b⁺ cells from tumor, spleen, blood, and BM and the longitudinal BrdU incorporation by monocytes/macrophages (Mφs) and neutrophils. (B) BrdU labeling kinetics of neutrophils (red circles) and monocytes/ Mφs (black squares) in tumor-bearing mice. Each time point represents the mean (± SD) of 3 mice.