ICAM1 gene maps on chromosome 19p13.3-p13.2 scanning 15512 bp.

7 exon; mRNA 3249 bp.

A transmembrane glycoprotein of 532 amino acids, which has a molecular mass ranging from 75 to 115 kDa. ICAM-1 is a member of the immunoglobulin supergenge family, and contains five extracellular immunoglobulin-like domains.

ICAM-1 is expressed on various cells of both hematopoietic and non-hematopoietic cells, including endothelial cells, leukocytes other than basophilic granulocytes, T cells, B cells, fibroblasts, and cancer cells.

ICAM-1, a member of adhesion molecules, binds to two integrins belonging to the beta2 subfamily CD11a/CD18 (LFA-1) and CD11b/CD18 (Mac-1) on the surface of leukocytes. ICAM1 is a key molecule in immune-mediated and inflammatory processes and function as a co-stimulatory signal which is important for the trans-endothelial migration of leukocytes and the activation of T cells. ICAM-1 can be induced under inflammatory condition by TNF-alpha in a process that involves IKK-beta. ICAM1 on target cells leads to recruitment of the MHC-I proteins to the contact area and enhances presentation of cognate peptide MHC-I complex to cytotoxic T cells. ICAM-1 interacts with important factors involved in many kinds of human cancers. ICAM-1 is involved in transmembrane signal transduction in the regulatory process of cell proliferation through the mitogen-activated protein kinase (MAPK) pathway and eventually the AP-1 pathway (Springer, 1990; Dustin et al., 1998; Simmons et al., 1988; Caras et al., 1987; Rothlein et al., 1986; Dustin et al., 1986; Tsujisaki et al., 1991; Gardiner et DSouza, 1999).