Exon 7 was replaced with an IRES-lacZ cassette and a floxed pgk-neo cassette via homologous recombination. Cre mediated recombination removed the neo cassette. At P28 beta-galactosidase activity is detected in hair cells of the cristae ampullaris and very faintly in in hair cells of the saccular and utricular maculae. (J:184419)