EDN1 and neoplasm: The significant effect of ET-1 receptor blockade in animals exposed to IH could thus be due to a specific effect of IH on endothelin expression in tumors, but also to the systemic nature of IH, which increases circulating ET-1 levels18 as well as tissue ET-1 levels in various organs, such as vessels19 and adipose tissue21, present in the tumor macroenvironment.