A construct containing a full length cDNA of Zfp423 with a single nucleotide insertion (3877_3878insT) between ZF 27 and ZF 28, corresponding to amino acid 1208 of the protein, followed by an IRES, YFP and a floxed neo selection cassette was inserted into the 5' UTR, replacing the first five exons of the locus. The insertion creates a termination codon and altered reading frame in all reading frames. Presence of the neo cassette severely impairs expression of the inserted construct. (J:190934)