Fig. 1

a Tubular structure formation of microvascular endothelial cells (MVECs) in Matrigel after 48 h of culture alone (before endothelial-to-mesenchymal transition [EndoMT]) or cocultures with fibroblasts. The fluorescent red images show that MVECs (post-EndoMT) have a decreased tube formation ability with respect to those treated with bosentan (BOS) and macitentan (MAC), which show a well-organized tubelike network. b The tube formation ability was measured as cells per millimeter and is expressed as the ratio of total tube length in each culture condition to the length in the culture of untreated (CTR) MVECs. Data are expressed as median (range) of six biological replicates (*p < 0.05, **p < 0.01). c Number of branching points expressed as mean ± SD of six biological replicates (*p < 0.05)