A beta-galactosidase/neomycin (beta-geo)cassette was inserted into intron 10 (also intron 7 of splice variant 2). RT-PCR analysis confirmed the expression of a fusion transcript (exons 1-10 fused to beta-geo) and a low level of wild-type RNA expression (about 10% that of wild-type controls) in homozygous mutants. (J:127121)