a, d, g, Representative haematoxylin and eosin staining of the indicated kidney structures. b, e, h, Representative immunohistochemistry staining of the indicated kidney structures for the proliferation marker Ki-67. c, f, i, Representative immunohistochemistry staining of the indicated kidney structures for the mesenchymal marker vimentin. In panels c, f, the vimentin-positive cells shown are stroma cells. In panel i, the vimentin-positive cells shown are mostly blastema components. a–c, WT epithelium; d–f, mutant epithelium; g–i, mutant blastema. All experiments were repeated twice with similar results. Scale bars, 50 μm.