BAC RPCI23-311C1 was engineered to contain the insertion of the EGFP/cre fusion, IRES, puromycin resistance cassette, polyadenylation sequence, loxP site, and F3-flanked neomycin resistance cassette into Six2 at the translation initiation site in exon 1. The pound symbol (#) is used when no line is specified and/or lines are pooled.