Materials

Human platelet TGF-β1 (R&D Systems, Abingdon, UK) was reconstituted in sterile 4 mM hydrochloric acid (HCl; VWR International Ltd, Lutterworth, UK) and 0.1% bovine serum albumin (BSA; PAA Laboratories GmbH, Pasching, Austria) that had been filter-sterilised through polyethersulfone membrane with 0.2 μm pore size (Sigma-Aldrich, Gillingham, UK). A stock solution of 10 ng/μl TGF-β1 was stored at − 80 °C until use. A vial of MS-SAFE protease and phosphatase inhibitors (Sigma-Aldrich) was dissolved into 2 ml 10 × RIPA lysis and extraction buffer (Sigma-Aldrich) and stored at − 20 °C as a stock solution. 1 × RIPA buffer was used to lyse cells and extract proteins. Bicinchoninic acid (BCA) protein assay (Thermo-Fisher Scientific, Paisley, UK) was used to measure protein concentration of cell lysates. Total collagen contents were measured indirectly through the measurement of hydroxyproline using the QuickZyme Total Collagen Assay (QuickZyme, Leiden, The Netherlands). Soluble collagens in conditioned media were colourimetrically detected by the Sircol soluble collagen assay (Biocolor Ltd., County Antrim, UK). Information of ELISA kits used in this study is listed in Supplementary table ⁹.