Figure 14. The fluorescent peptide substrate does not allow to measure reliably furin activity in cell lysates.

A, the cleavage of Pyr-RTKR-AMC by the supernatant aliquots (50 µg total protein for MCF-7 and LoVo cells and 5 µg total protein for U251 cells). RFU, relative fluorescence unit. B, the biosensor (100 pmol) was co-incubated for 2 h with the total cell lysates or with the purified furin (100 fmol). The digests were analyzed by Western blotting with the GFP antibody. Where indicated, dec-RVKR-cmk was added to the reactions. WB, Western blotting.