In addition, ABCG2 is known to mediate the efflux of gefitinib (Iressa) from cancer cells (Saito et al., 2006), and its expression is regulated by NRF2 (Singh et al., 2010) and the EGFR-tyrosine kinase cascade (Meyer zu Schwabedissen et al., 2006; Huang et al., 2011; Figure 1B). This evidence concerns the gene NFE2L2 and cancer.