Figure 6.

Oxygenation-tension and ALK5-dependent expression of collagen type II, next to PAI-1 and selected downstream targets ID and SP. Normalized relative mRNA expression of type II collagen (COL-II, i.e., COL2A1) next to that of ALK5-Smad2/3 downstream target PAI-1 (plasminogen activator inhibitor-1). Pharmacological inhibition of ALK5 (ALK5i) suggests its involvement in COL2A1 expression (A). Respective immunoblots showing protein abundances (B). Expression of ALK1-Smad1/5/8-target DNA-binding proteins inhibitor ID1 and ID3 and transcription factors SP1 and SP3, respectively (C). Selected oxygenation levels were 2.5% and 20% pO₂, respectively. RT-qPCR (n = 5), Western blot (n = 3); * p < 0.05, ** p < 0.01, *** p < 0.001.