BPI fold containing family B, member 4 (BPIFB4) is a protein that in humans is encoded by the BPIFB4 gene.[5] It was formerly known as "Long palate, lung and nasal epithelium carcinoma-associated protein 4" encoded by the LPLUNC4 gene. The BPIFB4 gene sequence predicts 4 transcripts (splice variants); 3 isoforms have been well characterized.[6][7] In a variety of mammals, BPIFB4 is generally expressed in very high levels in the olfactory epithelium (nasal mucosa), high levels in the gonads (testis, ovary) and pituitary, moderate levels in white blood cells (monocytes)[8][9][10][11] It can occur either localized in the cytoplasm of cells or secreted and circulated systemically in blood plasma.
