Most of exons 3 and 4 of the gene is replaced with b-galactosidase (b-gal)-Neo resistance cassette, which deletes 1630 bp and insert premature termination of Nek7 coding at amino-acid 75 but leaving intact the splice acceptor site of exon 3 and the splice donor site of exon 4. Western blot confirmed absence of protein product in cultured MEF. This is a null allele.