Abstract: Major histocompatibility complex class Ⅰchain related gene A(MICA) is located within the MHC class Ⅰ region of chromosome 6, including six exons. The MICA locus encodes membrane-bound polypeptides, similar with the classic class Ⅰ molecules, including three extracellular domains (α1, α2, and α3), a transmembrane domain, and a cytoplasmic tail, but is not associated with β2-microglobulin. MICA gene are expressed on endothelial cells, epithelial cells as well as most epithelial tumor cell surface, and are involved in the process of cell differentiation, proliferation and infiltration in a variety of tumor cells. Soluble MICA(sMICA) can be used as the prognosis predicting factor for some tumors. MICA gene plays an important role in the pathogenesis of a variety of malignant tumors, which might bring new ideas in prevention and treatment for malignant tumors.

Key words: Neoplasms, Tumor escape, Major histocompatibility complex class Ⅰ chain related gene A