Abcb1a^tm1Bor

A 1.6-kb fragment containing exons 6 and 7 and encoding the extracellular, transmembrane, and cytoplasmic domains, was replaced by the insertion of a hygromycin cassette. While low levels of transcript were detected in the intestines of homozygous mutant mice by RNAase protection assays, immunoblot analysis showed an absence of protein expression. (J:18554)