Ighm^tm2.1Bgmn

A puromycin resistance gene cassette with a 5' loxP site was inserted into exon 1 and 2 of the Igh Cmu gene segment, deleting 330bp of 3' of exon 1, intron 1 and 5' of exon 2. This insertion was done in ES cells that already had a neo cassette with a 3' loxP site in the alpha 3' enhancer of Igh Calpha (Rr151). Cre mediated recombination results in about a 200 kb deletion spanning the end of exon 1 to the alpha 3' enhancer. (J:118453)