Cover image for the February 2020 issue of Stem Cell Reports. Increasing MLL1 levels enhances the production of hematopoietic cells from a hemogenic endothelial intermediate through an altered intracellular signaling state. The cover image shows a stylized endothelial-to-hematopoietic transition with a halo of green representing Rac signaling activity as the cells change shape. The stylized drawing is superimposed on a confocal image of MLL1-induced embryonic dorsal aorta immunostained with CD31 (red) and Runx1 (green) antibodies, performed by Elizabeth Howell in Nancy Speck’s lab. Drawing by Donald Backos. The article this is based on is available at https://www.cell.com/stem-cell-reports/fulltext/S2213-6711(19)30448-5