Haploinsufficiency of Apc leads to lethality. (A) Analysis of the deletion of Apc in primary mice as determined by semiquantitative polymerase chain reaction of genomic DNA from bone marrow (BM) cells 4 days after induction. (B) Kaplan-Meier survival curve of primary Mx1-Cre⁺Apc^fl/+ (n = 13) and Mx1-Cre⁻Apc^fl/+ (n = 13) mice. (C) Peripheral blood counts of primary mice after induction. The deletion of a single allele of Apc was induced in Mx1-Cre⁺Apc^fl/+ mice treated with 3 doses of pI-pC, referred to as Δ/+ mice. Control Mx1-Cre⁻Apc^fl/+ mice are referred as fl/+ mice. The data were collected when Δ/+ mice became moribund within 3 to 8 months after induction. n = 13; ***P < .001.