NO-induced migration and cord formation requires MT1-MMP expression and activity. (A) HUVECs were treated with 1 μM bradykinin in the presence or absence of anti–MT1-MMP (mAb LEM-2/15) or control anti-CD31 and were seeded onto Matrigel. Cord formation was quantified after 6 hours. Data are the means plus or minus SD of the FI above tube formation by untreated cells from 3 experiments. The absolute value corresponding to FI = 1 was 59.5 cords/field. *P < .01 (versus NS); #P ≤ .01 (versus No Ab). All experiments were run in triplicate. (B) Top panel: Western blot of eNOS expression (phosphorylated and total) in MLECs from wild-type (+/+) and MT1-MMP null mice (−/−). Bottom panel: eNOS localization was visualized by immunofluorescence and NO production by DAF-FM labeling in wild-type and MT1-MMP–null MLECs. (C) MLECs from wild-type and MT1-MMP–null mice were induced to migrate on Transwell chambers during 16 hours by addition of 1 μM bradykinin in the upper chamber, or toward 10 nM CCL2 or CXCL12 in the lower chamber. Data are the means plus or minus SD of the fold induction (FI) from 4 independent experiments. The absolute value corresponding to FI = 1 was 15.25 migrated cells/field. *P < .03; **P < .02 (versus None); #P < .02 (versus MT1-MMP+/+ None). (D) Wild-type and MT1-MMP–null MLECs were treated as indicated with bradykinin (1 μM) or with CCL2 or CXCL12 (10 nM) and seeded onto Matrigel. Cord formation was quantified after 6 hours. Data are the means plus or minus SD of the FI above tube formation by untreated cells (None), of several independent determinations (n = 5 for None and bradykinin, n = 4 for CCL2, and n = 3 for CXCL12). The absolute value corresponding to FI = 1 was 50.7 cords/field. **P < .03; **P < .01; (versus None); # P < .01 (versus MT1-MMP+/+ None).