Effect of pro-angiogenic factors on endothelial cell OPG production. HuDMECs were treated with increasing concentrations of TNFα (a) and (b), VEGF (c) and (d), TGFβ (e) and (f), or FGF (g) and (h) for 24 hours. Conditioned medium was collected and OPG secretion measured using ELISA as described in materials and methods. RNA was extracted and gene expression quantified using real-time PCR. For real-time quantitative PCR, values were normalised to GAPDH and are given as fold expression compared to untreated HuDMECs. Data are represented as mean ± S.E.M. from three independent experiments performed in triplicate. ***, p < 0.001 compared to untreated control; **, p < 0.01 compared to untreated control; *, p < 0.05 compared to control.