Measurement of PS TFPI-cofactor activity in thrombin generation assays. The TFPI-cofactor activity of PS from WT or Pros^+/− plasmas was investigated in a CAT assay with very low levels of mouse TF (see “TFPI-cofactor activity in a CAT assay”). Mean thrombin generation curves of WT (n = 5) and Pros^+/− (n = 6) plasmas were measured under the following conditions: in the absence of anti-PS and anti–mouse TFPI antibodies (○); in the presence of DakoCytomation anti-PS antibodies (0.35 mg/mL, final concentration; ▲); in the presence of anti–mouse TFPI antibodies (0.17 mg/mL, final concentration; ●); and in the presence of both DakoCytomation anti-PS (0.35 mg/mL, final concentration) and anti–mouse TFPI (0.17 mg/mL, final concentration) antibodies (△).