provide insight into the molecular pathogenesis. The 3. Okey AB, Riddick DS, Harper PA. Molecular biology of the aroextracellular matrix deposition and gene expression matic hydrocarbon (dioxin) receptor. Trends Pharmacol Sci need to be measured and compared with other well-1994;15:226-232. 4. Okey AB, Riddick DS, Harper PA. The Ah receptor: mediator of characterized models of hepatic fibrosis. The activation the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and of the hepatic stellate cell (Ito or fat-storing cell) needs related compounds. Toxicol Let 1994;70:1-22. to be assessed in an in situ study. Also, the hepatic 5. Puga A, Nebert DW, Carrier F. Dioxin induces expression of c-fos levels of cytokines need to be measured. Dioxin has and c-jun proto-oncogenes and a large increase in transcription factor AP-1. DNA Cell Biol 1992;4:269-281. been shown to have a wide variety of effects on cyto-6. Fernandez-Salguero P, Pineau T, Hilbert DM, McPhail T, Lee kines in nonhepatic cells including a complex effect on SST, Kimura S, Nebert DW, et al. Immune system impairment the expression of the transforming growth factor b, 7 an and hepatic fibrosis in mice lacking the dioxin-binding Ah recepinduction of transcription of interleukin 1b, 8 and an tor. Science 1995;268:722-726. increase in tumor necrosis factor a levels. 7 Because 7. Dohr O, Vogel C, Abel J. Modulation of growth factor expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Exp Clin Immunogenet these three cytokines have been incriminated in he-1994;11:142-148.