KDM5B and breast cancer: KDM5A (0/24/66 hours) and KDM5B (66 hours) both remove H3K4me3.44,45 KDM5B regulates H3K4 methylation during ES cell differentiation and acts in concert with LSD1 to regulate H3K4 methylation at highly active ES cell genes.46 This lends credence to the idea of cooperation between pairs of demethylases leading to complete H3K4 demethylation in ES cells, as is the case for LSD1 and KDM5B in breast cancer cells.47