Crossing Aph1atm1Bdes with mice expressing cre in the germ line created this allele in which exons 2-7 were deleted via cre-mediated recombination, leaving a lacZ sequence with a 5' splice acceptor sequence downstream of exons 1 and 2. RT-PCR and Western blot of mutant MEFs demonstrated the lack of expression of mRNA or protein, respectively. (J:96106)