EPAS1, BHLHE73, HIF2A, MOP2, PASD2, Endothelial PAS domain-containing protein 1, Basic-helix-loop-helix-PAS protein MOP2, Class E basic helix-loop-helix protein 73, HIF-1-alpha-like factor, Hypoxia-inducible factor 2-alpha, Member of PAS protein 2, PAS domain-containing protein 2

This gene encodes a transcription factor involved in the induction of genes regulated by oxygen, which is induced as oxygen levels fall. The encoded protein contains a basic-helix-loop-helix domain protein dimerization domain as well as a domain found in proteins in signal transduction pathways which respond to oxygen levels. Mutations in this gene are associated with erythrocytosis familial type 4.