Down-regulates SLC1A2/EAAT2 promoter activity when expressed ectopically. Activates the nuclear factor kappa-B (NF-kappa-B) transcription factor. Promotes anchorage-independent growth of immortalized melanocytes and astrocytes which is a key component in tumor cell expansion. Promotes lung metastasis and also has an effect on bone and brain metastasis, possibly by enhancing the seeding of tumor cells to the target organ endothelium. Induces chemoresistance. Interacts with BCCIP, CREBBP/CBP and RELA/p65. In epithelial cells, recruited to tight junctions (TJ) during the maturation of the TJ complexes. A nucleolar staining may be due to nuclear targeting of an isoform lacking the transmembrane domain (By similarity). TNF-alpha causes translocation from the cytoplasm to the nucleus. Widely expressed with highest levels in muscle-dominating organs such as skeletal muscle, heart, tongue and small intestine and in endocrine glands such as thyroid and adrenal gland. Overexpressed in various cancers including breast, brain, prostate, melanoma and glioblastoma multiforme. By TNF (at protein level). By HIV-1 infection of primary fetal astrocytes. Knockdown significantly reduces the adhesion of cancer cells to lung microvascular endothelial cells and the reciprocal effect is observed following overexpression. Was originally thought to be a type II membrane protein but this is inconsistent with the results of multiple phosphorylation studies because this topology would locate the phosphorylation sites in the lumen or extracellularly rather than in the cytoplasm.