YAP and TAZ mediate endothelial tubulogenesis, vacuolation, and sprouting angiogenesis. (A) Phase contrast images of 3D ECFC vasculogenesis in oligomeric collagen matrices (G’ = 132 Pa). (B and C) ECFC tubulogenesis on Matrigel: tube length (P < 0.0032; B) and number (P < 0.0003; C). n = 12; two-way ANOVA with Tukey’s post hoc test. (D and E) ECFC-embedded oligomeric matrices recovered from NOD-scid mice. (D) Functioning vasculature and human endothelium visualized using Rhodamine lectin and Alexa Fluor 647 anti-human CD31, respectively. (E) Chromogenic HRP substrate DAB (brown) was used to visualize YAP, TAZ, CTGF, and CYR61. (F–H) Whole mTomato-expressing aortas were extracted, segmented, and embedded in collagen for the aortic sprout assay. (F) mTomato-expressing cell outgrowth from aortic explants. (G) Cell outgrowth, average distance from the explant edge. n = 17–21 rings; P < 0.001; two-way ANOVA with Tukey’s post hoc test. (H) The sum of vascular sprout lengths from explants. P < 0.03; two-way ANOVA with Tukey’s post hoc test. (I) Schematic of the transcriptional negative feedback loop that regulates intracellular tension. Cytoskeletal tension is increased by ROCK activation of myosin II causing YAP and TAZ nuclear localization. Active YAP and TAZ inhibit ROCK-mediated MLC phosphorylation by transcriptional control of NUAK2 and ARHGAP 28 and 29 expression, preventing overactivation of myosin II. Repeated significance indicator letters (e.g., a–a) signify P > 0.05, while groups with distinct indicators (a vs. b) signify P < 0.05.