TFPI overexpressed in VSMCs inhibits monocyte TF activity. Immunoprecipitation of cellular extracts (A) or conditioned supernatant fluid (B) from ³⁵S-labeled untreated (VSMC), control virus–transfected (Ad5lacZ), or TFPI-transfected (Ad5TFPI–c-myc) rabbit VSMCs with either control antibody (lanes 2, 4, 6, and 8), antibody specific for human TFPI (lanes 1, 3, and 5), or the c-myc epitope (lane 7). Inhibition of factor Xa activity (C), TF/VIIa-complex activity on factor X (D), and of LPS-induced U937 monocyte TF activity (E) by untreated (▨), Ad5lacZ-transfected (▪), and Ad5TFPI–c-myc–transfected (□) rabbit VSMCs determined by chromogenic assay. Data are expressed as mean ± SD; *P < .01, **P < .001.