FIG. 2.

Limitation of level of CYP1A1 mRNAs induced by CYP1A1 activity. Northern blots were prepared by using 20 μg of HepG2 cell mRNAs in each lane and probed with a labeled human CYP1A1 cDNA. Cells were treated for 72 h with the compounds mentioned below. After 36 h, the culture medium was changed and the treatment was resumed. BP (2.5 μM) was used in order to induce CYP1A1 mRNAs. (A) In addition to BP, the indicated concentrations of catalase were added to the culture medium. (B) In addition to BP, ellipticine (10 μM) was added, or not, to the culture medium.