A loxP site flanked neomycin resistance gene cassette and the 5.2 kb human pseudogene were inserted into intron 2. The neo cassette was removed through subsequent cre-mediated recombination. The pseudogene contains a CpG island that is differentially (maternally) methylated and has promoter function in human. Mice derived from ES cell clone 42 were used for further breeding. (J:207568)