Widely expressed, highest levels found in brain, placenta, spleen, testis, and ovary. Up-regulated in some tumor cells. By IFNA1. Elicits IgG antibody response in a subset of polycythemia vera patients and as well in patients with chronic myelogenous leukemia and prostate cancer receiving IFNA1 or other therapy, suggesting that it is broadly immunogenic. This protein is produced by a bicistronic gene which also produces the MTPN protein from a non-overlapping reading frame. LUZP6 belongs to a group of cryptic antigens without conventional genomic structure. It is encoded by a cryptic open reading frame located in the 3'-untranslated region of MTPN that is expressed following IRES-mediated alternative initiation of translation at a AUU start codon.