Fig. 1. Targeted disruption of maspin. (A) Targeting strategy. Homologous recombination replaces the seventh exon with the neomycin resistance (neo) gene. Note the change of SacI (S1) into BamHI in the construct. Restriction site are (S1) SacI; (Xh1) XhoI; (K1) KpnI; (B1) BamHI; (Xb) XbaI; (Sa1) SalI. (B) Southern blot analysis of Mp^+/+ and Mp^+/– ES cells. The genomic DNAs were digested with a SacI enzyme and the blot was probed with ³²P-labeled SacI-SacI fragment (3.6 kb). The 3.6 kb band was from the wild-type allele. A novel 12 kb band indicated the presence of the targeted allele. (C) RT-PCR analysis of maspin mRNA expression in Mp^+/+ and Mp^–/– embryoid bodies.