Srf^tm1Nor

An 880 bp genomic fragment containing the initiation codon and sequences encoding the dimerization and DNA binding domains was replaced with a neomycin selection cassette. RT-PCR analysis showed that no detectable transcript was produced from this allele in mutant embryos (data not shown). Activity assays in extracts derived from homozygous E8.5 embryos demonstrated that no functional protein was present, and immunohistochemistry experiments on sections of E8.5 homozygous embryos confirmed that no encoded protein was detectable. (J:50876)