RUNX2 and congenital bilateral aplasia of vas deferens from CFTR mutation: However, in aortic valve leaflets with advanced CAVD, RUNX2 expression could be detected in CD31+-endothelial cells (58.33 ± 2.12%), and 39.08 ± 1.23% of valve interstitial cells expressed both CD31 and RUNX2 proteins, suggesting endothelial cell transdifferentiation (Figure 1E).