APC cleavage of factor VIIIa or EDC cross-linked factor VIIIa. Bovine APC (0.045 μmol/L) and PSPCPE (100 μg/mL) were added to factor VIIIa or EDC cross-linked factor VIIIa (0.9 μmol/L) and reactions (600 μL) were incubated 16 hours at 37°C. After addition of SDS sample buffer, reactions were subjected to electrophoresis on 12% gels, transferred to PVDF, and immunoblotted with the following antibodies: C5 (A), R8B12 (B), or anti-FVIII^403-427 (C). Lane 1, factor VIIIa; lane 2, APC-cleaved factor VIIIa; lane 3, cross-linked factor VIIIa; and lane 4, APC-cleaved cross-linked factor VIIIa.