Hand1^{tm2.1(Hand1)Abfi}

The coding region of Hand1 from a 600-bp cDNA initiating at the ATG and terminating at the stop codon followed by an EGFP expression cassette and a PGKNeo cassette flanked by loxP sites were inserted in frame at the position of the initiation codon. The PGKNeo cassette from Hand1tm2(Hand1)Abfi was removed via cre-mediated recombination. EGFP expression is not detected in E9.5 embryos. qRT-PCR indicates that heterozygotes express about 50% of wild-type mRNA levels while homozygotes express at 30% that of wild-type, indicating that this is a hypomorphic allele. In situ analysis indicates that expression is not uniformly reduced throughout the embryo. (J:164028)