Apposition-dependent regulation of PAI-1 is unaffected by inhibitors of the PA system and effectors of latent TGF-β activation. (A) In situ hybridization of L-fibroblast cells (L)/LE-II endothelial cells (E) grown in the presence of 100 mmol/L mannose-6-phosphate (brightfield, left and darkfield, right). (B) β-Gal activity in fibroblasts (L) transfected with a PAI promoter-LacZ plasmid and cocultured with LE-II cells (E) in the presence of 200 mg/mL Soybean Trypsin Inhibitor.