At the maturation stage of amelogenesis, the retained enamel matrix in the ShhGFPCRE/Bmp2f/f/Bmp4f/f and ShhGFPCRE/Bmp2+/f/Bmp4f/f mutant teeth was wavy, and in each mutant tooth, subsets of mutant maturation-stage ameloblasts underwent single or collective emigration from the ameloblast layer and formed, together with other epithelial cells of the enamel organ, prominent tumor-like nodules, some of which encompassed enamel matrix-like material. This evidence concerns the gene BMP2 and neoplasm.