TGF-β1 regulates PAC differentiation and function. (A) VEGFR2 expression in BM-derived progenitors isolated from WT mice (A) or TGF-β1⁺/⁺ or TGF-β1^+/− mice (B) and grown in the presence or absence of TGF-β1 (A) for 7 days (n = 3 per group). Percentage of VEGFR2 expression was analyzed by flow cytometry. *P < .01 versus no TGF-β1; **P < .01 versus TGF-β1^+/−. (C) BM-derived progenitors grown in the presence of Ctrl (vehicle) or TGF-β1 and plated in fibronectin-coated wells were assessed for adhesion (n = 6 per group). HPF indicates high power field. *P < .05 versus Ctrl. (D) BM-derived GMPs and MEPs were grown in the presence or absence of TGF-β1 treatment were assessed for VEGFR2 mRNA expression by quantitative PCR (n = 3 per group). *P < .01 versus Ctrl; **P < .05 versus Ctrl. (E) TGF-β1–stimulated expression of the VEGFR2 promoter-luciferase reporter transfected in BM-derived GMPs and MEPs (n = 3 per group). *P < .01 versus Ctrl; **P < .05 versus Ctrl.