Fig. 3. In vitro processing of recombinant pro-CPA by purified cathepsins. Activated recombinant cathepsin E (1.5 ng or 15 ng; A) or cathepsin D (300 ng or 2 µg; B) was added to 1 µl recombinant CPA at pH 5.5. As a control, pro-CPA was incubated without added cathepsins. Samples were incubated at 37°C for 30 minutes and subjected to western-blot analysis using specific antiserum for CPA and pro-CPA. As a control, cell extracts prepared from wild-type BMMCs were included in the western-blot analysis. The BMMC extracts contains both the pro and the active forms of CPA.