Interleukin-20 (IL-20) belongs to the family of IL-10-related cytokines, which includes IL-10, -19, -20, -22, -24 and -26. IL-20 induces STAT activation through two types of receptor complex, one of which it shares with IL-19, indicating that their biological activities may overlap. Both cytokines may play an important role in regulating the development and proper functioning of skin. IL-20 has also been shown to promote endothelial cell tube formation, suggesting that it may be involved in vascular vessel maturation and remodelling.