Gemcitabine (purity > 98%), cycloheximide (purity > 93%) and MTT (purity > 98%) were purchased from Sigma-Aldrich (St. Louis, USA). LY294002 (purity > 98%) was purchased from Beyotime Institute of Biotechnology (Shanghai, China). Digoxin (purity > 97%), etoposide (purity > 99%), paclitaxel (purity > 99%), cisplatin (purity > 99%), 5-Fluorouracil (5-FU, purity > 99%), cytarabine (ara-C, purity > 99%), doxorubicin (purity > 99%) and MG132 (purity > 97%) were purchased from Selleck Chemicals (Houston, USA). Actinomycin D (purity > 95%) was purchased from KeyGen (Nanjing, China). Anti-NQO1, anti-HO-1 and anti-GCLC antibodies were obtained from Santa Cruz Biotechnology (Texas, USA). Anti-Keap1, anti-Nrf2, anti-p-Akt, anti-Akt, anti-p-P38 and anti-P38, anti-p-ERK1/2, anti-ERK1/2, anti-p-JNK and anti-JNK antibodies were purchased from Cell Signaling Technology (Danvers, USA). Anti-ABCC1 and anti-ABCC5 antibodies were purchased from ABclonal (Wuhan, China). Anti-β-actin and anti-ubiquitin antibodies were obtained from Bioworld (Minnesota, USA). Anti-lamin A antibody was obtained from Sigma-Aldrich (St. Louis, USA).