KDM5B and LSD1 co-regulate H3K4 methylation in ES cells. (A) Venn diagram showing overlap of KDM5B- and LSD1-bound genes in ES cells. (B) Bright field microscopy of shLuc and shKdm5b ES cells cultured in the presence of 2 μM of the LSD1 inhibitor tranylcypromine/parnate (LSD1i) for 4 days. (C) Correlation between changes in histone methylation and expression level. Fold change normalized tag density ratios of H3K4me3, H3K4me2, and H3K4me1 at refseq genes were sorted into four groups based on their absolute expression level. Note that the lowest expressed genes have increased H3K4me3/2/1 levels in LSD1i-treated ES cells (red line, highest 25% expressed; green line, lowest 25% expressed).