Fig. 4.
Endothelial cell delta-like protein-4 (Dll4) deficiency selectively reduces myosin phosphatase-targeting subunit 1 (MYPT1) content. A: representative immunoblot showing reduced aortic Dll4 and MYPT1 content with preserved myosin light chain kinase (MLCK) levels in tamoxifen (TM)-treated (+TM) vascular endothelial cadherin-CreERT2 [VeCad-CreERT2 (Ve)]/Dll4 flox/flox (Dll4f/f) mice. Data were normalized to Ve−Dll4f/f (control or Cre−) and represent means ± SE (n = 4). Data were analyzed using a t-test, *P = 0.0005 and **P = 0.0026. B: representative immunoblots displaying preserved smooth muscle myosin heavy chain (SMMHC) and smooth muscle α-actin (SMA) content in Dll4-deficient (Ve+Dll4def) vessels. Data are means (SD) (n = 4) normalized to GAPDH and control (Cre−) lane and were analyzed using a t-test, P = not significant (Cre− vs. Cre+). C: representative elastin-stained control and Dll4-deficient aortic cross sections. Vessels are morphologically indistinguishable with intact elastic lamina; boxes are ×40 magnification of low-power (×10) views (arrows).