Fig 1.

Targeted disruption of the CHF1/Hey2 gene. (a) The gene for CHF1 consists of five exons within ≈15 kb of genomic DNA. The targeting construct will remove 551 bp of upstream promoter, exons 1 and 2, and the majority of exon 3. These exons encode the N terminus, the basic region, and the majority of the helix–loop–helix domain. (b) Southern blot showing DNA fragments generated after digestion of wild-type and knockout genomic DNA and probing with the 5′ probe. (c) RT-PCR showing the absence of CHF1 mRNA expression and no compensatory increase of CHF2 and CHF3 expression in cardiac ventricles of E18.5 knockout mice. (d) Ventricular septal defect in E18.5 embryo.