This transgene consists of a tandem duplication of the 285 bp B-block/block 3 enhancer of the mouse Lfng gene, the beta globin basal promoter, the open reading frame encoding chicken LFNG with a C-terminal FLAG tag, and the SV40 3' UTR and polyadenylation signal. The Lfng B-block enhancer drives expression in the cranial presomitic mesoderm (PSM) stripe adjacent to the incipient somite border. Thirteen lines were generated. This line expresses the transgene in the cranial stripe and only very weakly in the caudal presomitic mesoderm.