Scientists explored the function of the reprogramming factor KLF4 within production of induced pluripotent stem cells (iPSCs). KLF4 was shown to bind upstream of the Tcl1 target gene, which controls a metabolic change in energy era during the acquisition of cellular pluripotency. This helps explain how tissues turn back the developmental clock from adult to come cell, and could be harnessed to improve efficiency or restrict genetic damage during iPSC generation.