The transgenic construct contains a 9kb sequence of the 5' portion of the mouse Hlxb9 (Mnx1) gene, a 5' splice substrate, an enhanced Green Fluorescent Protein (EGFP) open reading frame, and a bovine growth hormome polyadenylation site sequence. Line 1 contains 10 to 11 tandem copies of the transgene. The expression pattern of this transgene is the same as that for the endogenous gene from which the promoter is derived.