5.5 kb of upstream bovine AMELX gene sequence plus untranslated exon 1 and intron 1 was fused to a bovine LRAP cDNA, and followed by a bovine polyadenylation signal sequence from the bovine AMELX gene. RT-PCR analysis demonstrated that this transgene is expressed in tooth germ by 15 days of fetal age, and western blot analysis demonstrated protein expression in molar tooth germs. Four lines of transgenice mice were produced; in addition to line 9, lines 15, 16 and 22 were made.