Figure 6.

 Papain and cathepsin B inhibition assay. Capan‐1 cells were cultured and incubated for 24 h with or without the addition of 1 μm cystatin C to the medium. After lysate preparation, centrifugation and heat denaturation of the endogenous cysteine proteinases, the cysteine protease inhibitory capacity of the cell lysate was determined by measuring the inhibition of (A) papain and (B) cathepsin B. As positive and negative controls, instead of cell lysate, Brij or E‐64 was used (n = 1). Z‐Phe‐Arg‐AMC was used as the substrate and the fluorescence was measured after 30 min incubation. Each experiment consisted of three wells for each condition. An average of the result from two samples from each well was calculated. The same experiment was then repeated another day. Results are expressed as mean ± SD (n = 6). Statistical analysis was carried out using Mann–Whitney U‐test.