Biological functions of maspin.

Maspin (Mammary Serine Protease Inhibitor) was first reported in 1994 as a serpin with tumor suppressive properties. Maspin was initially isolated through subtractive hybridization and differential display analysis as a 42-kDa protein that is expressed in normal mammary epithelial cells but reduced or absent in breast carcinomas (Zou et al., 1994). Further research led to maspin's characterization as a class II tumor suppressor based on its ability to inhibit cell invasion, promote apoptosis, and inhibit angiogenesis (Sheng et al., 1996; Zhang et al., 2000b; Jiang et al., 2002). Since then, efforts have been made to characterize maspin's tumor suppressive mechanisms. In particular, researchers have studied maspin localization, the regulation of maspin expression, and more recently, maspin protein interactions. By elucidating these mechanisms, researchers are beginning to understand the complex, pleiotropic nature of maspin and the pathways through which maspin exerts its tumor suppressive properties. These new findings not only further enhance our understanding of cancer biology but also provide an avenue to develop maspin's potential as a diagnostic marker for cancer progression, and as a potentially powerful therapeutic agent in the fight against breast cancer. (c) 2006 Wiley-Liss, Inc.