C1 inhibitor and HRG regulate the plasminogen activator function of αFXIIa. The impact of inhibitors on αFXIIa-polyP₇₀ plasminogen activator function was monitored in the absence (black) or the presence (gray) of PAI-1 (1 nM), PAI-2 (1 nM), C1 inhibitor (500 nM), or HRG (1 μM) by absorbance-based clot lysis (A) or by plasminogen activation assay in which plasmin was detected by cleavage of S2251 (B). For simplicity, the controls in the absence of polyP₇₀ are not shown, because no lysis was observed in either the absence or presence of the inhibitor. Data represent mean ± SEM (n = 3).