With specific designed prmers. CYP2B6 and CYP1A1 cDNA were generatecl by reverse transcrlI7tion-Polymerase chain reaction（RT-PCR ）technlque Performed on total RNAs isolated frorn hum1ln liver and 3-rnethylch（

lanthrene（3-Mtt）induc human amnion FL

cells. Cell llnes （CHL

2B6 and CtHL-1A1 ） capableof expressing hunlan cytochome P 15O （CYP ） 2B6 and 1A1 were establishecl after transfection of corre-sponding eukaryotic reconlbinant expression plasmid with human CYP2ll6 and 1A1 cDNA lnserts respectlvely. These cell lines stably expressed the mRNAs and the enzymatic activltles cc）rresI’onding to ttYP2B6and CYP1A1

respectively’ Compared with Chinese hamster lung （CHL） cells

the n1icr（）nucleus frecluencyin CHl

-2B6 cells is markedly lncreased when exPosed to nitrosamines

aflatoxln B

（AFB1） and cyclophos-Phamide （CPA）. Thls is also in CHL-1A1 cells

when exposed to carcinogenic polycycllc aromatic hydrocar-bons.