Cell Culture Protocols for Reporter Assays

The HepG2 40/6 stable DRE-driven reporter line was generated and cultured, as previously described [15 (link)]. The Hepa 1.1 stable DRE-driven reporter cell line was obtained from Dr. Michael Denison (University of California, Davis, CA, USA) and cultured under the same conditions as HepG2 40/6 cells. The human epithelial colorectal adenocarcinoma cell line Caco-2 was obtained from ATCC and maintained in α-minimal essential medium (Sigma, Hong Kong, China; M0894), supplemented with 20% fetal bovine serum (Gemini), 100 U/mL penicillin, and 100 μg/mL streptomycin; for actual treatments, the medium was replaced by a medium containing 5% serum. HN30 cells were obtained and cultured, as previously described [16 (link)]. LS174T cells (ATCC #3521130) were cultured with α-minimal essential medium supplemented with 8% (v/v) fetal bovine serum, 100 U/mL penicillin, and 100 µg/mL streptomycin. All cells were grown in a humidified incubator at 37 °C, with 95% air and 5% CO₂.