Dioxin-Induced nuclear translocation of GFP-AHR within mammalian (J774A.1) and fish (JF) cell line was tested and compared. J774A.1 and JF cells were transfected with GFP-AHR expression vector. After 4 hours of 10-6M dioxin treatment, the nuclear translocation of GFP-AHR is examined by the fluorescence of GFP and effect of dioxin is evaluated. Dioxin-induced nuclear translocations of GFP-AHR were observed in both types of cells. In comparisons, JF cells seem to response to dioxin better in terms of translocation of AHR.