TIE1 and cholangitis: One of the studies that assessed melatonin actions on angiogenesis employed an in vivo model of cholangitis‐derived fibrosis; results indicated that melatonin prevented the increase of vascular endothelial growth factor receptor 2 (VEGFR‐2), VEGFR‐3, VEGF, angiopoietin 1 and 2, Tie‐1, Tie‐2 and Von Willebrand factor (VWF) expression (Wu et al., 2017).