Hematopoietic stem cells take advantage of 'junk' RNA to replenish the blood system Chemotherapy is widely used to treat cancer patients. During the treatment, chemotherapeutic agents affect various biochemical processes to kill or reduce the growth of cancer cells, which divide uncontrollably in patients. However, the cell-damaging effect of chemotherapy affects cancer cells but also in principle many other cell types, including cycling blood cells. This puts the hematopoietic system under severe stress and pushes hematopoietic stem cells (HSCs) in the bone marrow to produce fresh cells and replenish the stable pool of differentiated blood cells in the body. Researchers from the MPI of Immunobiology and Epigenetics, together with colleagues from the University of Freiburg, Lyon, Oxford, and St Jude Children's Research Hospital in Memphis, now discovered that hematopoietic stem cells make use of RNA molecules from junk DNA sections to enhance their activation after chemotherapy.