Sequence extending from within exon 6 through exon 11, including the region encoding the ETS DNA binding domain, was replaced with a neomycin selection cassette inserted by homologous recombination. Though no normal or endogenous alternatively spliced transcripts were detected in homozygous mutant mice, a stable transcript corresponding to the targeted allele was identified by RNAse protection. Normal protein was undetected by Western blot analysis of MEFs, however, the lack of an amino-terminal antibody prevented the ruling out of the presence of a truncated protein. (J:66012)