Potential mechanisms and cross talk of endothelium prolyl hydroxylase 2 (PHD2) in regulation of angiotensin II-mediated renal fibrosis, reactive oxygen species (ROS) formation, and iron metabolism. AT1R, angiotensin II type 1 receptor; HIF, hypoxia-inducible factor; PHD2ECKO, endothelial PHD2-specific knockout.