E2f3^tm4Gle

A floxed neo cassette was inserted 108 bp upstream of the E2f3 isoform "a" start codon, the exon 1b open reading frame replaced the exon 1a open reading frame, and a third loxP site was inserted approximately 300 bp downstream of exon 1a. Western blot analysis of MEFs confirmed the absence of expression of the "a" isoform with retention of expression of the "b" isoform. (J:138289)