This allele was derived from Enpp2tm1Vart, in which a neomycin selection cassette was inserted upstream of exon 1, and the neo cassette and exons 1 and 2 were flanked by loxP sites. Both exons and the selection cassette were then excised by Cre-mediated recombination to generate the knock-out allele. The absence of protein expression was confirmed by immunohistochemistry on E9.5 embryo extracts. (J:134373)