The sequence encoding amino acids 62-375 was replaced with an in frame nls-lacZ cassette followed by a floxed neomycin resistance gene. This deletes almost the entire the forkhead/winged-helix domain. The neomycin gene was subsequently excised. Western blot analysis of protein extracts from neonatal ovaries detected only lacZ fusion proteins and not the wild-type protein. (J:87737)