In these studies, the effects of KMT2D loss on H3K4 methylation were examined using mammalian cells with MLL3-null states (e.g., human HCT116 colon cancer cells, mouse brown adipocytes, and mouse embryonic stem cells) because KMT2D and MLL3 (homologues of the Drosophila H3K4 methyltransferase Trr) are closely related to each other. The gene discussed is KMT2D; the disease is malignant colon neoplasm.