Long-term exposure to Pb leads to PKC activation in rat livers; however, Pb also inhibited the activity of PKCα in a human hepatoma cell line (Liu et al. 1997; Tonner and Heiman 1997), and the inhibition was much more pronounced when Pb levels were high (Sun et al. 1999). The gene discussed is PRKCA; the disease is hepatocellular carcinoma.