Mammary Serine Protease Inhibitor (Maspin)

Maspin is a serpin and tumor suppressor gene.It has been associated with prostate cancer and breast cancer.It has also been associated with tumors of the pancreas.It was identified in 1994.In normal cells expressing SERPINB5, the SERPINB5 promoter is unmethylated and the promoter region has acetylated histones and an accessible chromatin structure. In contrast, normal cells that do not express SERPINB5 have a completely methylated SERPINB5 promoter with hypoacetylated histones, an inaccessible chromatin structure, and a transcriptional repression that is relieved by inhibition of DNA methylation. These findings indicated that cytosine methylation is important in the establishment and maintenance of cell type-restricted gene expression.