Mir155^tm1.1Rsky

A modified bacterial artificial chromosome (BAC) targeting vector was used to replace a 0.97 kb portion of exon 2 of the bic/mir-155 gene with an in-frame b-galactosidase (lacZ) reporter gene (with polyA sequence and followed by a loxP-flanked neomycin resistance cassette). The mice were bred with a cre-deleter strain (congenic C57BL/6 background) to remove the loxP-flanked selection cassette. The resulting bic/mir-155 mutant mice (with lacZ followed by a single remaining loxP site). In heterozygotes, approximately 60% of germinal center (GC) B cells express the lacZ reporter whereas the vast majority of the non-GC B cells do not. (J:121084)