['Tissue factor pathway inhibitor-2 (TFPI-2) regulates matrix metalloproteinases activation and extracellular matrix degradation. Over-expression of TFPI-2 enhances atherosclerotic plaque stability. The aim of this study is to investigate the effect of conditional knockout (KO) of TFPI-2 in vascular endothelial cells on the initiation and development of atherosclerotic plaque.', 'A Cre/mloxP conditional KO system and Tek-Cre mice were used to generate offsprings with monoallelic deletion of the TFPI-2 gene in endothelial cells. TFPI-2(fl/+)/Tek-Cre mice, TFPI-2(fl/+) mice and ApoE(-/-) mice (n=6 for each group) were included. Arteries were obtained. HE, EVG and anti-α-SMA staining were used to examine the morphology of vessel and plaque. Protein expression and phosphorylation were detected by Western blot or immunohistochemistry.', 'TFPI-2(fl/+)/Tek-Cre mice were generated. TFPI-2 level decreased to 40.68% in TFPI-2(fl/+)/Tek-Cre group. TFPI-2(fl/+)/Tek-Cre developed plaques when no plaque was found in TFPI-2(fl/+) mice. Compared with ApoE(-/-) group, TFPI-2(fl/+)/Tek-Cre group has smaller plaque area, decreased lipid content and less buried fibrous cap layers. MMP-2 and MMP-9 in TFPI-2(fl/+)/Tek-Cre group was higher than in TFPI-2(fl/+)group. The phosphorylation of PPAR-α and PPAR-γ was decreased in TFPI-2(fl/+)/Tek-Cre group.'] Does conditional knockout of tissue factor pathway inhibitor 2 in vascular endothelial cells accelerate atherosclerotic plaque development in mice?