Maspin is a novel epithelial-specific serine protease inhibitor (serpin).Maspin expression correlates with epithelial differentiation and better prognosis of cancer.Conversely down regulation of maspin is associated with increased tumor invasion and metastasis.Experimental envidence demonstrates that expression of maspin not only inhibits tumor invasion and metastasis, but also induces cell redifferentiation and sensitizes cells to drug-induced apoptosis.We showed that both endogenous maspin and endogenously expressed maspin inhibits the activity of histone deacetylase Ⅰ (HDAC 1).Interestingly, the maspin-mediated HDAC 1 inhibition requires glutathione s-transferase.