Stat3^Δ/ΔNcr1-iCreTg mice show enhanced tumor surveillance in leukemia and lymphoma models in vivo. (A-B) A total of 10⁶v-abl⁺ leukemic cells were injected subcutaneously in the flanks of Stat3^fl/fl and Stat3^Δ/ΔNcr1-iCreTg mice. After 12 days, tumor weight was determined (A). (B) Bar graphs summarize data of 3 independent experiments with n ≥ 14. (C) Kaplan-Meier plot of Stat3^fl/fl (n = 7) and Stat3^Δ/ΔNcr1-iCreTg (n = 9) mice after IV injection of 10⁶v-abl⁺ leukemic cells. One representative experiment of 2 independent experiments is shown. Mice were euthanized at the first signs of paralysis and poor health. (D) Newborn Stat3^fl/fl (n = 12) and Stat3^Δ/ΔNcr1-iCreTg (n = 7) mice were infected with a replication-incompetent ecotropic retrovirus encoding for v-abl by subcutaneous injection. Mice were euthanized at the first signs of paralysis and health detractions. One representative experiment of 3 independent experiments is shown. (E) Hematoxylin and eosin stains of blood and bone marrow of Stat3^fl/fl and Stat3^Δ/ΔNcr1-iCreTg mice suffering from v-abl–induced leukemia.