A "hit and run"-type vector was used to create a CTA to TTA mutation in codon 2179 (codon 2153 in the original publication) in sequences corresponding to the apo-B48 editing codon. Western blot analysis on plasma derived from heterozygous and homozygous mice demostrated that the expression of the ApoB100 isoform is unaffected by this mutation, while no ApoB48 isoform is produced from this allele. (J:33830)