We have demonstrated that treatment of endothelial cells with conditioned medium from breast cancer cells and cytokines that are elevated in breast cancer patients induces S-nitrosylation of endothelial barrier proteins (p120, VE-cadherin and β-catenin) promoting phosphorylation and perturbation of the interactions among these proteins that leads to their internalization, which destabilizes the endothelial barrier (Marín et al., 2012; Guequén et al., 2016; Zamorano et al., 2019). The gene discussed is CDH5; the disease is breast cancer.