Our experimental evidence suggests that where maspinWT fails to compete against X′ for HDAC1 in the nucleus of poorly differentiated tumor cells, subtle differences in maspin RCL and its neighboring regions, such as maspinD346E, may restore the nuclear presence (Figure 8C) as well as the nuclear activity of maspin, and ultimately restore epithelial differentiation [12]. The gene discussed is SERPINB5; the disease is neoplasm.