TCDD was obtained from Dr. Steve Safe (Texas A&M University) and was handled and disposed of in accordance with University of California safety policies. The chemical library of 176 compounds obtained from Dr. Bruce Hammock (University of California, Davis) was described previously.9 (link) Fetal bovine serum (FBS) was obtained from Atlanta Biologicals (Lawrenceville, GA), and Geneticin (G418) and Alpha Minimal Essential Medium (α-MEM) were from Invitrogen (San Diego, CA). CALUX cell lines H1L6.1c3 (mouse hepatoma (Hepa1c1c7)), H4L1.1c4 (rat hepatoma (H4IIe)), G16L1.1c8 (guinea pig intestinal adenocarcinoma (GPC-16)), and HG2L6.1c1 (human hepatoma (HepG2)) were previously described.22 (link), 23 (link)