Wide spread of pollutants present in the environment, has a profound deleterious effect on the interacellular homeostasis and may affect the gene expression. Among the most common hazards found in today's environment are the toxic metals and metalloids. Several metals have been found to produce acute and chronic tissue injury in humans and animals. It has been suggested that, one class of such toxic metals is the heavy metals as cadmium (Cd), Zinc (Zn), Copper (Cu), and Mercury (Hg). Exposure to one or more heavy metals (e.g. Cd, Cu, Ag, Zn, and Hg) had been found to elevate metallothionein...

Multidrug resistance (MDR) is a kind of resistance of cancer cells to multiple classes of chemotherapic drugs that can be structurally and mechanistically unrelated. Classical MDR regards altered membrane transport that results in lower cell concentrations of cytotoxic drug and is related to the over expression of a variety of proteins that act as ATP-dependent extrusion pumps. P-glycoprotein is the most important and widely studied member of the family that belongs to the ABC superfamily of transporters. It is apparent that, besides its role in cancer cell resistance, this protein has...