An 1808 bp cDNA fragment of the mouse Grhl2 gene was inserted such that the codon 12 of exon 2 of Grhl3 was fused to the corresponding codon of Grhl2. This insertion replaced part of exon 2 and all of intron 3 and exon 3. In addition a floxed neo cassette was inserted after the cDNA and then removed by Cre mediated recombination. RT-PCR analysis confirmed the expression of the fusion gene in homozygous and heterozygous mice and absence of expression of the endogenous gene in homozygous mice.