A) The genomic and mRNA location of the Bay Genomics pGT0Lxf vector (gene trap) on chromosome 17 corresponding to the Abcf1 locus in the XK097 ES cell line. The locations and names of the primers used for screening are in round brackets. The size of the PCR product is indicated in square brackets. B) The ES cell line, XK097, contains the gene trap sequence between exon 7 and 8 in the Abcf1 gene. Genomic DNA analysis of the XK097 cell line (left panel) compared with a wild type ES cell line (right panel). “IB” (Int1-f and Bay cDNA (1250bp)) primer combination indicates the presence of the gene trap cassette in the Abcf1 locus. “-” is the negative water alone control and “+” is the positive control (Rps15 (350bp)) for the PCR. C) RT-PCR of the ES cell line, XK097, produces a transcript containing exon 7 and the Bay Genomics vector sequence. RT-PCR analysis of the XK097 cell line (Abcf1+/-; left) compared with a wild type ES cell line (Abcf1+/+; right). 7 = Ex7-f-Bay-cDNA primers, F = Ex7-Ex8 primers, β = β-actin primers.