Second injury induces regeneration in regeneration-defective wounds. (A) Diagram of the double-wounding assay. (B) Representative pictures of single-wounded larvae (a) and double-wounded larvae (b) at 3 d after wounding. Dotted lines indicate tail transection. (C) Quantification of regenerated tail fin length at 3 d after wounding (single wound/DMSO: 9 larvae; single wound/DPI: 14 larvae; single wound/PP2: 10 larvae; double wound/DMSO: 13 larvae; double wound/DPI: 15 larvae; double wound/PP2: 15 larvae). Horizontal lines indicate means. (D) Immunofluorescence of pSFK at 0.5 h after second wounding. *, P < 0.05; one-way ANOVA with Dunnett’s posttest. Bars, 50 µm.