(A-B). Cushion explants were cultured under CS (compressive stress), CS +VP (compressive stress +YAP inhibitor), U+VP (unloaded +YAP inhibitor) conditions for 24 hr. (C). After 24-hr-culture, explants were stained for YAP (green) and proliferation marker pHH3 (red, arrows), or (D). YAP (green) and VE-Cadherin (red). (E). Circularity of explants cultured under different stress conditions, which describes how close a valve is to a perfect sphere. (F). Percentages of cells expressing pHH3 under different culture conditions. (G). Average intensities of VE-Cad expression under different culture conditions, the intensities are normalized to maximum intensity. Data are presented by mean ± SEM, n=15 explant valves from eight embryos, *p<0.05, two-tailed student t-tests.