M180Tg and LRAPTg represent the major amelogenin isoforms, while CTRNCTg represents the major amelogenin cleavage product. M180Tg contains exons 2, 3, 5, 6a–6d, 7; CTRNCTg contains exons 2, 3, 5, 6a-part of 6d; LRAPTg contains exons 2, 3, 5, 6d, 7. Amino acid numbers and sequences corresponding to transgene exons are shown. Orange arrowhead indicates the site of the first MMP20 cleavage.