SMAD3 limits polymorphonuclear neutrophil production and function. (A) Phenotypic analysis of BM cells harvested from WT and SMAD3-KO littermates (n = 5). LSK are Sca-1⁺ and c-kit⁺ but negative for the following lineage markers: CD3ϵ, B220, Gr-1, CD11b, Ter119, CD11c, NK1.1, and TCR-γδ). Common myeloid progenitors (CMP) are Lin⁻Sca-1⁻c-Kit^hiCD34⁺CD16/32⁻. Granulocyte monocyte progenitors (GMP) have the same phenotypic profile as CMP but express high levels of CD16/CD32. (B) Granulocyte (CD11b⁺/Gr-1⁺) and (C) monocyte (CD11b⁺/Gr-1⁻) counts harvested after culture for 10 days in methylcellulose-based medium in the absence or presence of exogenous TGF-β (10 ng/mL; n = 5 independent experiments). (D) DHR mean fluorescence intensity (MFI) of Gr-1⁺ cells after brief phorbol myristate acetate stimulation (n = 4). All histograms represent the mean and SEM. Statistical differences according to the 2-tailed paired t test: *P < .05, **P < .01.