"When anemia or hypoxia occurs transcriptional factor hypoxia-inducible factor (HIF) binds to EPO 5' hypoxic response element and EPO gene transcription increases. In CKD pericytes transdifferentiate to myofibroblasts and subsequently the ability of EPO production decreases leading to renal anemia. Recent advances on epigenetics create a new field to study EPO gene expression at chromatin level."xsd:string