Two papers in this issue reveal new insight into lung regeneration. Rosen et al. (p 869) report that preconditioning by sublethal radiation allows better engraftment of embryonic lung tissue into the injured lung of adult mice, leading to improved lung repair. Liu et al. (p 866) find by lineage tracing that c-kit+ cells do not, as previously reported, contribute to lung epithelium during homeostasis or repair after injury, but rather maintain an endothelial fate. Image shows a colored scanning electron micrograph of normal lung tissue, including the lumen of a blood vessel (yellow) lined with endothelial cells, as well as alveoli air sacs lined with capillaries (blue and pink). Image credit: Professor Pietro M. Motta / Science Source.