ASPP1 gene-trapped clone. (A) Sequences of 5′ and 3′ RACE products. Lowercase letters represent ASPP1 cDNA sequence including cording region (bold). Capital letters represent the En2 splice acceptor (5′ RACE) or Pax2 splice donor sequence (3′ RACE) derived from the gene-trap vector. Underline indicates a Pax2 intronic sequence. (B) Schematic representation of genomic structure of ASPP1 wild-type and gene-trapped loci. Boxes represent exons and the cording region is filled. The integration site of the gene-trap vector is indicated by an asterisk. H indicates HindIII; X, XbaI. (C) In vitro expression of lacZ reporter for ASPP1. EF indicates undifferentiated ES cells on embryonic fibroblast; EB, embryoid body; days 4, 5, and 6, differentiated ES cells on the OP9 feeder cell layer. Scale bars, 50 μm.