Scientists reveal that during hematopoietic regeneration, RNA expressed from a part of the genome considered ‚junk DNA‘ is used by hematopoietic stem cells to get activated and proliferate. The study shows that these so-called transposable elements make RNA after chemotherapy and activate an immune receptor which induces inflammatory signals enhancing hematopoietic stem cell cycling and thus participating in the regeneration of the hematopoietic system.