BMP-2 activation of β-C transcriptional activity in hPAECs is dependent on ERK. (A) Western immunoblots of hPAECs stimulated with BMP-2 in the presence or absence of 10 μM PD98059. Blots were probed for pERK, total ERK, GSK3-β, and β-C. (B) Western immunoblots of hPAECs transfected with dominant-negative (Δ) Smad1 or -3 constructs and stimulated with 10 ng/ml BMP-2 for 1 h. Blots were probed for active β-C and α-tubulin as a loading control (CON). (C) Western immunoblots of hPAECs incubated with 10 ng/ml BMP-2 in the presence or absence of 500 ng/ml DKK 1 for 1 h. Blots were probed for active β-C and α-tubulin as a loading control. Error bars denote mean ± SEM for three different experiments performed in triplicate. **, P < 0.001 and ***, P < 0.0001 (vs. control).