Transgenic Abi-1^KOmice show splenomegaly, leukocytosis, thrombocytosis, and decreased survival. (A) Schematic representation of the experimental design of deleting Abi1^flox allele in Abi1(fl/fl);Tg(Mx1-cre)(⁺) mice by poly(I:C) induction. Analyses were conducted on animals at 14, 35, or 56 weeks of age (4, 25, or 46 weeks after recombination, respectively). (B) Genomic PCR analysis of Abi1^flox deletion efficiency in tail (top) and bone marrow (bottom) DNA. PCR amplification of the mutated, LoxP site containing Abi1 allele produces a 359-nt band, recombined Abi1 allele produces no band, and nonmutated wild type Abi-1 allele produces a 179-nt band. A locus map is presented in supplemental Figure 2A. Tissue from 3 different Abi-1^WT, Abi-1^HET, and Abi-1^KO animals was used. (C) Western blot analysis of Abi-1 protein levels in the bone marrow of Abi-1^WT, Abi-1^HET, and Abi-1^KO mice. Tissue from 3 different animals per group was used. (D) Representative gross anatomy of femurs and spleens of 14-, 35-, and 56-week-old Abi-1^WT or Abi-1^KO animals. (E) Average spleen and liver sizes of Abi-1^WT and Abi-1^KO mice. Relative organ weight was calculated as an absolute organ weight (g)/body weight on sacrifice day (g) ×100. Organs from n = 12 sex-matched animals were evaluated per age group. (F) Average white blood cells count, hematocrit values, and platelet count of the peripheral blood obtained from 14-, 35-, and 56-week-old Abi-1^WT or Abi-1^KO animals performed using automated hematology analyzer. Peripheral blood from at least 12 sex-matched mice was analyzed per each age group. *P < .05, **P < .01, ***P < .001. (G) Survival of Abi-1^WT (n = 48) or Abi-1^KO (n = 60) animals monitored from birth for 67 weeks (log-rank P = .003).