Allele-specific expression analysis of Vwf in (B6 × WSB) F1 mice. Adult lung cDNA was prepared from F1 mice (n = 3 males and 3 females). Polymerase chain reaction was performed with exonic primers flanking a T/C SNP, followed by primer extension with a fluorescently labeled primer and dATP, dGTP, dTTP, and ddCTP, which results in differentially sized products in each strain (A). Fluorescent primer extension products were separated, quantitated, and compared with genomic standards (B). B6 and WSB genomic DNA were mixed in various proportions to produce the standard curve. Results are expressed as a percentage of B6 transcripts from total transcripts. Linear regression was performed with Microsoft Excel.