Due to the impact of MLL4 on mitochondrial metabolism apparent in the upregulation of genes enriched in the mitochondrial respiratory chain complex I pathway in MLL3/4-KO mESCs (Supplemental Figure 6E), we separately treated colorectal cancer cells with the mitochondrial Complex I inhibitors Piericidin A or Phenformin. The gene discussed is NDUFV1; the disease is colorectal cancer.