2.5. Total RNA extraction and real-time PCR Total RNAs were isolated from the seeded cells in 60 mm2 plate by using the TRIzol reagent (Thermo Fisher Scientific Inc., Waltham, MA, USA) and processed for the synthesis of cDNAs. Reverse-transcription (RT) reactions were conducted by incubating 200 ng of the total RNAs with a reaction mixture. The mixture is containing 0.5 μg/μl oligo dT12- 18 and 200U/μl Moloney Murine Leukemia Virus RT (Life Technologies). Then, relative quantification of mRNA levels were performed using Roche LightCycler (Roche, Mannheim, Germany) with the SYBR Premix ExTaq system (Otsu, Japan) [41]. All primers were synthesized by Bioneer and the primer sequences for mouse Keap1, nqo1, Nrf2, Smad7, TβR1, Smurf1, and 18sRNA are shown in Table 1.