Maintenance of imaginal disc plasticity and regenerative potential in Drosophila by p53

► DNA damage accumulates in irradiated p53 mutants, impairing regeneration. ► Cell death is not necessary for induction of regeneration. ► During regeneration cell division continues at a developmentally programmed pace. ► Irradiation induces p53-dependent larval timing and disc patterning checkpoints. ► Compensatory proliferation is not restricted to the larval stage of development.