EIG121 (Estrogen-induced gene 121 protein) is thought to play a role as a marker of hyperestrogenic state and estrogen-related type I endometrial carcinoma. It belongs to the UPF0577 family. It is a 1013 amino acid single-pass transmembrane protein that, though expressed in normal endometrium, is overexpressed in endometriod tumors. As an evolutionarily conserved gene, EIG121 is also expressed during early xenopus development, showing maximum expression at the gastrula stage.Synonyms: Estrogen-induced gene 121 protein, UPF0577 protein KIAA1324