FIG. 1.

Hus1 allelic series. (A) Schematic representation of the Hus1 alleles generated in systems for constitutive and conditional Hus1 inactivation. The first four Hus1 exons are shown as boxed numbers. A neomycin resistance cassette (NEO), frt sites (lined rectangles), and loxP sites (solid triangles) are shown. Exposure of alleles containing frt sites to the Flp recombinase or alleles containing loxP sites to the Cre recombinase excises the intervening sequence, generating a new allele as indicated. (B) Northern blot analysis of primary MEF cultures. Total RNA was prepared from individual MEF cultures of the indicated genotypes and hybridized with a ³²P-labeled Hus1 or Gapdh cDNA probe. RNA prepared from each MEF culture was loaded in duplicate.