A gene trap vector inserted into the endogenous gene such that the beta-galactosidase and neomycin genes were fused to the expressed mRNA at position 1149. Beta-galactosidase expression was noted in a similar pattern to the wild-type mRNA. RT-PCR analysis indicated that a low level of wild-type transcript was still expressed from this allele, suggesting that this mutation is a hypomorph. (J:69466)