“…On the other hand, the metabolism of these metal ions, their sites of regulation, and their overall regulatory functions are as yet poorly understood. This is true despite the fact that a number of studies have been carried out on the biological consequences of high concentrations of bivalent metal ions, including studies of toxicity (Fassett, 1975;Sunderman, 1977), mutagenicity (Ochi and Ohsawa, 1983), malignant transformation in vitro (DiPaolo and Casto, 1979) and tumor induction (Furst and Haro, 1969;Sunderman, 1977).…”