KEAP1 and neoplasm: To clarify whether NRF2 has any active role in promoting tumor-initiating activity, which is one of the important properties for aggressive tumorigenesis (Supplementary Fig. 1a, b), we cultured three NRF2-activated NSCLC cell lines with KEAP1 mutations, A549, H460 and H202330, under low attachment conditions in defined stem cell medium to allow them to grow in the form of oncospheres31.