Cleavage of mPlg activated by uPA. A. SDS-PAGE showing the products of purified mPlg (38.5 KD) after being activated using uPA. The same results were obtained when SAK was used. Lane 1 is a molecular weight marker and Lane 2 is the activated mPlm. B. Diagram of fragments R1, R2-1, R2-2, and R3. The left arrow shows the authentic activation cleavage between R561 and V562. This cleavage results in normal activation fragments R1 (25.2 KD) and R2-1 (13.3 KD). The right arrow shows the non-specific cleavage between K698 and E699, which results in extra-fragments of R2-2 (15.0 KD) and R3 (10.2 KD).