 Dcytb mRNA and protein levels in the gut are increased by iron deficiency and hypoxia which acts to promote dietary iron absorption.The effect of iron deficiency and hypoxia on Dcytb levels are medicated via the HIF2 (Hypoxia inducible factor 2) transcription factor which binds to hypoxia response elements within the Dcytb promoter and increases transcription of the gene.DCYTB protein has also been found in other tissues, such as lung epithelial cells and in the plasma membrane of mature red blood cells of scorbutic species (unable to make ascorbate) such as human and guinea pig but not in other species which have retained the ability to synthesise ascorbate like mice and rat.