{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nEpithelial membrane protein‐2 (EMP2) is a multifunctional tetraspan protein that critically regulates the trafficking and surface expression of key membrane receptors. In several studies, EMP2 was shown to interact selectively with specific integrin heterodimers—such as β1‐containing complexes—and to modulate their membrane distribution. In endometrial cells, increased EMP2 expression enhanced the surface display of integrins like α6β1 and αvβ3, thereby improving adhesion properties that are essential for blastocyst attachment. In glioblastoma models, EMP2 up‐regulation was linked to increased αvβ3 levels, activation of focal adhesion kinase and Src kinases, and ultimately promoted tumor cell invasion."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "3"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nEMP2 also plays an important role in organizing plasma membrane microdomains. It facilitates the trafficking of glycosylphosphatidylinositol‐anchored proteins (GPI‐APs) into lipid rafts while simultaneously suppressing caveolin expression, which in turn diminishes the formation of caveolae. These alterations in membrane compartmentalization can influence downstream signaling processes and cellular responses."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn additional immunologic roles, EMP2 modulation has been associated with enhanced antigen presentation and immune cell interactions. Overexpression of EMP2 increases the surface levels of major histocompatibility complex class I and adhesion molecules, heightening susceptibility to cytotoxic lymphocyte‐mediated killing. Moreover, in the lung alveolus, EMP2 expressed by type I epithelial cells supports the proper transepithelial migration of neutrophils, thereby influencing innate inflammatory responses during pneumonia."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn reproductive biology, EMP2 is crucial for establishing endometrial receptivity and successful implantation. During the window of implantation, EMP2 translocates to the apical cell surface where it aids in the delivery of integrins such as αvβ3. This function is modulated by steroid hormones and is linked to proper uterine immune cell homeostasis; alterations in EMP2 levels have been shown to affect the proportions of uterine natural killer cells and macrophage subtypes, thereby influencing pregnancy outcomes."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "8", "end_ref": "10"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond its roles in cellular trafficking and reproduction, EMP2 influences developmental processes and serves as a promising target in cancer diagnostics. Disruption of Emp2 in mouse embryonic stem cells resulted in prolonged expression of pluripotency markers, delayed mesoderm formation, altered epithelial–mesenchymal transition, and impaired cardiomyocyte differentiation. In parallel, EMP2’s preferential expression in malignant tumors has prompted investigations into its utility as an imaging biomarker for improved diagnostic and prognostic evaluation in oncology."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "11"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nFinally, EMP2 displays a distinct subanatomic distribution in ocular tissues, where it is localized in several epithelial layers and neural structures. This unique localization—differing from other tetraspan family members—suggests a specialized role in the regulation of apical membrane recycling and possibly in visual function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "13"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Madhuri Wadehra, Ramaswamy Iyer, Lee Goodglick, et al. 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