MTDH (metastasis adhesion protein), also known as astrocyte elevated gene-1 protein (AEG1) or lysine-rich CEACAM1 co-isolated protein (LYRIC), is a 582 amino acid single-pass membrane protein. Overexpressed in various cancers, MTDH activates the transcription factor NFκB and promotes anchorage-independent growth of immortalized astrocytes and melanocytes, which are key components of tumor growth. MTDH is also thought to enhance the seeding of tumor cells to the target organ endothelium. Localized mainly to the endoplasmic reticulum membrane, MTDH also translocates from the cytoplasm to the nucleus when induced by TNFα. MTDH also localizes to tight junctions (TJ) during the maturation of TJ complexes in epithelial cells. MTDH is found at highest levels in heart, skeletal muscle, tongue and small intestine.