HMOX1 and lung cancer: To verify whether these five somatic mutations in KEAP1 influence the function of KEAP1, WT and five KEAP1 mutants were stably transfected with retroviral vectors into A549/H460 lung cancer cell lines that carry loss-of-function mutations in KEAP1. As expected, nuclear NRF2 protein levels and expression of the NRF2 target gene HO-1 were significantly decreased after A549 or H460 lung cancer cell lines were stably transfected with WT KEAP1 (Fig. 2a).