Western blots were performed as described previously 24 (link) using antibodies specific for Bmi1, SOD2, Slug (Cell Signaling Technology, Beverly, MA, USA), Nanog (Aviva Systems Biology, San Diego, CA, USA), C-myc, ABCG2 (ATP-binding cassette transporters) (Santa Cruz, Dallas, Texas, USA) and GAPDH (Sigma, San Louis, MO, USA). The results obtained from western blot were quantified by Quantity One software (Bio-Rad) and shown in Supplementary Material: Figure S2.