A 760 bp gene fragment including 560 bp of promoter region and exon 1 was flanked by loxP sites. An FRT flanked PGK-neo cassette was inserted as well. Mice were crossed with an unspecified flp-deleter mouse to excise the selection cassette. Exon 1 including the translationaql start codon and the promoter region were excised by crossing to Tg(EIIa-cre)C5379Lmgd mice. (J:173391)