Increased expression of catalytically active but not inactive MT1-MMP increases EC lumen and vascular guidance tunnel formation. (A) ECs transfected with the indicated adenovirus were cultured for 24 hours, fixed, stained, and photographed. Adenoviral vectors used were control GFP, MMP-1, wild-type MT1-MMP (MT1-MMPWT), and mutant MT1-MMP (E240A) to inactivate the catalytic activity of the enzyme (MT1-MMPEA). Mean lumenal area in micrometers²  was measured, with bars representing area ± SD (P < .01). Blockade of this response is seen in all cell types by the addition of 5 μM GM6001, a broad-spectrum chemical MMP inhibitor. (B) Mean vascular guidance tunnel area was measured in micrometers,²  with bars representing area ± SD (P < .01). Blockade of this response is seen in all cell treatments after the addition of 5 μM GM6001, a broad-spectrum chemical MMP inhibitor. (C) Increased expression of MT1-MMP but not other proteins leads to increased EC lumenal area. Cultures were fixed and stained after 24 hours and photographed. Bar equals 50 μm. (D) Western blot analysis demonstrates increased expression of MT1-MMP in ECs after adenoviral infection with AdMT1-MMP but not other adenoviruses.