Figure 3: Quercetin induction of mitochondrial biogenesis requires CO. (a–c) HepG2 cells were exposed to 15 μM of quercetin for 3 h with or without 20 μg/mL of Hb. (a) Expression of PGC-1, NRF-1, and TFAM mRNA was determined by RT-PCR. (b) Expression of COX IV protein was determined by Western blotting. β-actin served as the standard. (c) Expression of mitochondrial DNA (mtDNA) content was quantified by real-time PCR. Relative amounts of mtDNA and nDNA contents were compared. Results are expressed as mean ± SE of three independent experiments, and representative data are shown. * compared with untreated control group; compared with cells treated with quercetin alone.