This allele was generated by inserting a conditional by inversion (COIN) cassette containing a rabbit beta-globin polyA site, EGFP and inverted lox site variants (lox71/lox66) in inverse orientation into the antisense strand exon1. This is functionally a wild-type allele, but cre-mediated recombination will yield a null allele detectable by expression of enhanced green fluorescent protein. (J:188991)