Figure 4.

Growth defect in Usf2(−/−) mutant mice. (A) All pups in one litter produced by a Usf2 heterozygous breeding pair were weighed at various times of postnatal development. Subsequent genotyping by tail DNA analysis revealed that the two smaller animals were homozygous mutants and that the wild-type and heterozygous pups all displayed similar weights. (B–D) Photographs of Usf2(−/−) mutants next to one of their siblings at birth (B) and at 6 days (C) or 1 month of age (D). Note the smaller size and proportionate body features of the mutants and the characteristic kinky tail of the newborn USF2-null pup.