The floxed neo cassette was excised from Vegfatm3Pec by the in vivo expression of cre recombinase, leaving the isoform specific cDNA replacement intact. The resultant allele lacks exon 6 as well as splice sites and thereby produces a single isoform with intermediate solubility and receptor binding properties. The exclusive presence of this isoform was verified by quatitative RT-PCR. (J:75507)