Gata1^tm1Mym

In order to weaken activity of the erythroid-specific promoter, homologous recombination was used to insert a neo cassette into the intergenic region between a GATA motif known to positively regulate transcription and the first erythroid specific exon (IE). The GATA is located approximately 620 bp 5' to IE. RT-PCR showed that gene expression in mutant male embryos was less than 5% of the level of expression in wild-type embryos. (J:40321)