Zinc is an essential micronutrient that is tightly regulated in humans and other animals and requires specialized mechanisms for its uptake, transport and excretion. Zinc metabolism has been extensively studied in both man and rodents, and zinc transport has received much attention with in vitro models. Numerous investigators have used isolated cell types, including hepatocytes, fibroblasts, endothelial cells and intestinal cells to help further characterize zinc transport. Of particular interest is the intestinal Caco-2 cell model. Caco-2 cells, a human colonic tumor cell line, have been studied considerably in the last decade as a model for drug, macronutrient and micronutrient absorption and transport. There are several characteristics that render Caco-2 cells an ideal model for absorption and transport. These cells can grow in monolayers and, upon confluency, the cells differentiate and become polarized. They form tight junctions and possess a brush border with functional brush border enzymes and thus resemble enterocytes. Due to these inherent characteristics, we have focused on Caco-2 cells to characterize the regulation of expression of the two zinc transporter gene families, ZnT and Zip, under conditions of zinc deprivation and supplementation. The current hypothesis is that ZnT family transporters decrease intracellular zinc concentration, while Zip family transporters increase intracellular zinc concentration. The human zinc transporter genes studied were ZnT1, 4, 5, 6, and 7, and Zip-1, -3, and -4. The Caco-2 cells were treated with TPEN, a cell permeable zinc chelator, at 1.25, 2.5 or 5.0 μM, zinc sulfate at 40 or 80 μM, IL1