The lasting influence of LSD1 in the blood An enzyme called LSD1 that controls the development of blood cells by manipulating gene expression in progenitor cells could be a therapeutic target for leukemia.

nside the nucleus, DNA is tightly packaged around scaffold proteins called histones to form chromatin. Histones control how easy it is for proteins—notably those involved in transcrib-ing the DNA sequence into messenger RNA—to access the DNA, so they have a critical role in regulating gene expression. Lysine residues within histones, particularly histones H3 and H4, are susceptible to many types of modification, including the addition of acetyl, methyl or ubiquitin groups. These modifications, often referred to as histone ‘marks’, influence how compact the chro-matin is and help to recruit protein complexes that activate or repress transcription. Although knockouts of histone-modifying enzymes are often lethal in mice, gene deletions that are restricted to specific tissues or time periods pro-vide valuable insights into how these enzymes choreograph cell fate. Now, in