STAT3 hyperactivation suppresses TGF-β activity on hematopoietic progenitor cells in gp130Y757F/Y757F bone marrow. (A) Liquid cultures of bone marrow-derived megakaryocytes were grown in serum-free media containing either IL-6 or IL-11 (100 ng/mL) in the presence of TGF-β1 (10 ng/mL) for 4 days. Cell cultures were cytocentrifuged and megakaryocytes scored by staining for acetylcholinesterase activity. (B-C) In vitro colony formation of bone marrow cells in semisolid agar cultures containing (B) SCF (50 ng/mL), IL-3 (10 ng/mL), TGF-β1 (10 ng/mL), IL-6 (100 ng/mL), and IL-11 (100 ng/mL), and (C) GM-CSF (10 ng/mL) and TGF-β1 (10 ng/mL). Data from 4 to 6 mice of each genotype are expressed as the mean ± SD. *P < .05 versus data from cultures within each genotype without TGF-β1.
