Nucleotide substitutions result in the amino acid substitution of Cys 4 of saposins A and B located in exon 4 (saposin A domain) and exon 7 (saposin B domain) with phenylalanine. Cre-mediated recombination removed the floxed neomycin resistance cassette inserted upstream of the modified exon 7. Western blot analysis confirmed the absence of saponin A and B, overexpression of saponin C and normal expression of saponin D in the cerebrum and liver.