Deleted in malignant brain tumors 1 protein, also known as glycoprotein 340, surfactant pulmonary-associated D-binding protein, DMBT1 and GP340, is a secreted protein which belongs to the DMBT1 family. DMBT1 contains 2 CUB domains, 14 SRCR domains and 1 ZP domain. It is highly expressed in alveolar and macrophage tissues. In some macrophages, expression is detected on the membrane, and in other macrophages, it is strongly expressed in the phagosome/phagolysosome compartments. Defects in DMBT1 are involved in the development of glioma (GLM). Gliomas are central nervous system neoplasms derived from glial cells and comprise astrocytomas, glioblastoma multiforme, oligodendrogliomas , and ependymomas.  DMBT1 may be considered as a candidate tumor suppressor for brain, lung, esophageal, gastric, and colorectal cancers. It may play roles in mucosal defense system, cellular immune defense and epithelial differentiation. DMBT1 may play a role as an opsonin receptor for SFTPD and SPAR in macrophage tissues throughout the body, including epithelial cells lining the gastrointestinal tract. It may be an important factor in fate decision and differentiation of transit-amplifying ductular (oval) cells within the hepatic lineage. DMBT1 may function as a binding protein in saliva for the regulation of taste sensation. It binds to HIV-1 envelope protein and has been shown to both inhibit and facilitate viral transmission.