2.10. Cathepsin cleavage studies

Cathepsin L (CL) or cathepsin B (R&D systems) were incubated with a molar excess of ps20 in 50 mM MES buffer with 4 mM DTT (pH 5.5) for 1 h at 37 °C +/− inhibitors E-64c or E-64d (Sigma). Reactions were stopped by addition of WB loading buffer and samples were analysed as described. For the modified ELISA assay; following ps20 crosslinking to fibronectin by TG as described above, CL was prepared in 50 mM MES with 4 mM DTT (pH 5.5) and added to ELISA plates for 2 h at 37 °C. Washing and detection were as described above.