Types of toxic responses -- Organ-selective toxicity -- Cellular transport and selective accumulation of potentially toxic xenobiotics -- Bioactivation of xenobiotics to reactive metabolites -- Xenobiotic-induced oxidative stress: cell injury, signaling, and gene regulation -- Disruption of cellular calcium homeostasis -- Mechanisms of necrotic and apoptotic cell death -- Impairment of cell proliferation and tissue repair -- Covalent binding of reactive metabolites to cellular macromolecules -- Immune mechanisms -- Cytokine-mediated toxicity -- Specific inactivation of enzymes and other proteins -- Interactions of xenobiotics with ion transporters -- Nuclear receptor-mediated toxicity -- Activation or disruption of cellular signal transduction by xenobiotics -- Disruption of mitochondrial function and mitochondria-mediated toxicity -- Novel mechanisms derived from systems toxicology.