A construct consisting of an FRT site, splice acceptor site, IRES, LacZ gene, loxP site neo cassette, FRT site and loxP site was inserted upstream of exon 2 and a loxP site was inserted downstream of exon 3 via homologous recombination. Cre mediated recombination removed the neo cassette and exons 2 and 3. LacZ expression was detected in the organ of Corti. qRT-PCR analysis confirmed the absence of mRNA expression in homozygous mutant mice.