miR-146a suppression impairs IL-1β downregulation of Smad4 and upregulation of vascular endothelial growth factor. Chondrocytes were transfected with miR-146a inhibitors and treated with or without IL-1β for 24 hours. (A) miR-146a inhibitors decreased IL-1β-induced upregulation of miR-146a. NC, negative control. (B) The inhibitory effect of IL-1β on Smad4 expression was counteracted by miR-146a inhibitors. (C) Vascular endothelial growth factor (VEGF) expression was significantly reduced by miR-146a inhibitors with IL-1β treatment at the RNA level. Values are the mean ± standard deviation (SD) of at least three independent experiments. **P < 0.01. (D) On the protein level, miR-146a inhibitors counteracted IL-1β-induced downregulation of Smad4 and upregulation of VEGF. The relative expression levels of protein are shown at the bottom of the bands as normalized by GAPDH level. (E) Densitometric analysis of immunoblot band intensities for Smad4 normalized by GAPDH. Data are mean ± SD of three independent experiments. (F) Densitometric analysis of immunoblot band intensities for VEGF normalized by GAPDH. Data are mean ± SD of three independent experiments.