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. 2014 Apr 4;9(4):e93899. doi: 10.1371/journal.pone.0093899

Figure 1. Time and pH-dependence of matriptase zymogen autoactivation in cell-free setting.

Figure 1

The insoluble fractions of cell homogenates prepared from 184 A1N4 mammary epithelial cells were exposed to phosphate buffers at pH(A), pH 7.0 (B) or pH 6.5 (C) at room temperature for the indicated time. Lysates were prepared and assayed by immunoblot analyses for matriptase with mAb M24 (which recognizes the 70-kDa matriptase zymogen and 120-kDa activated matriptase-HAI-1 complex) or for HAI-1 with mAb M19 (which recognizes the 55-kDa HAI-1 and 120-kDa activated matriptase-HAI-1 complex). Note that both antibodies also recognize degraded forms of the activated matriptase-HAI-1 complex. (D) Kinetics for induction of matriptase activation in cell-free homogenates. Representative data showing the ratio of activated matriptase relative to total matriptase (activated plus zymogen matriptase) for each pH plotted against time using Image J.