This article is available online at http://www.jlr.org linked ␣ -and  -subunit, with each subunit having a large extracellular domain, a single membrane-spanning domain, and a short, noncatalytic cytoplasmic tail. Integrins seem to be the major receptors by which cells attach to components of the extracellular matrix (ECM), such as vitronectin, etc. ( 4 ), and are involved in the metastasis signaling of hepatocellular carcinoma (HCC) ( 5 ).The integrin ␣ V subunit associates with one of fi ve integrin  subunits,  1,  3,  5,  6, or  8, to form fi ve distinct ␣ V  heterodimers ( 6 ). The integrin ␣ V  heterodimers on the cell surface interact with cell adhesive proteins, such as collagen, fi brinogen, fi bronectin, and vitronectin. These interactions play an important role in cell adhesion or migration, especially in tumor metastasis. Integrins increase in invasive tumors and distant metastases, characterize the metastatic phenotype, and play a key role in tumor metastasis ( 7,8 ). Many studies have documented marked differences in the surface expression and distribution of integrins between malignant tumors and preneoplastic tissues. For example, the integrin ␣ V  3 complex is strongly expressed in the invasive front cells of malignant melanoma and angiogenic blood vessels, but it is weakly expressed on preneoplastic melanomas and quiescent blood vessels ( 9 ). Also, it has been demonstrated that ␣ V  3 integrin is specifi cally required to sustain neovascularization induced in vivo by fibroblast growth factor-2 ( 10 ). Integrin ␣ V  3 physically associates with phosphorylated and activated insulin-like growth factor receptor, and it may be involved in the HCC cell migration and progression ( 11 ). Furthermore, inducing the expression of the integrin ␣ V ( 7 ) or  3 ( 12 ) subunit in melanoma cells increases their metastatic potential. Integrins have been implicated as very important adhesion molecules that are involved in multiple physiological processes, such as cell adhesion, proliferation, and survival ( 1-3 ). Each integrin generally consists of a noncovalently
Abstract Integrin is important in migration and
