a, Level of expression of pri-miR-21, pre-miR-21 and mature miR-21 or SMAD4 after treatment with BMP4 (2 h) in PASMCs transfected with control siRNA (Control-siRNA) or SMAD4 siRNA (SMAD4-siRNA). b, Level of expression of pri-miR-21, pre-miR-21 and mature miR-21 or PAI-1 in human SMAD4-negative breast carcinoma MDA-MB-468 cells stimulated with TGF-β (0.5 h) (*P < 0.05; n = 3). c, MDA-MB-468 cells were treated with TGF-β (1 h) before RNA-ChIP. Endogenous proteins were precipitated with anti-SMAD1/SMAD5, anti-SMAD2/SMAD3 or anti-DROSHA antibodies, followed by PCR analysis with a miR-21 primer (*P < 0.05, compared to none; n = 3). d, MDA-MB-468 cells were infected with adenovirus carrying dominant-negative type I TGF-β receptor (dnALK5), an inhibitor of TGF-β signalling, before TGF-β treatment (1 h). The amount of pri-miR-21, pre-miR-21 and mature miR-21 was examined (*P < 0.05, compared to none; n = 3). Error bars represent s.e.m.