Csnk1a1^–/+Trp53 mutant leukemias in tertiary transplants are sensitive to A51 treatment. (A) Schematic representation of tertiary sublethally irradiated (6 Gy) WT recipients of secondary Csnk^–/+p53-transformed bone marrow cells (untreated controls, n = 6; A51-treated, n = 10). A51-treated mice received A51 compound (5 mg/kg per day) starting at 8 days after transplant, 5 days per week until 4 weeks after transplant (euthanasia). (B) White blood cell and platelet counts of control and A51-treated mice at 4 weeks after transplant (euthanasia). (C) Spleen-to-bodyweight ratio in control and A51-treated mice. (D) Percentage of blasts in peripheral blood and bone marrow, and bone marrow cellularity in control and A51-treated mice at 4 weeks after transplant (euthanasia). (E) HE staining of bone marrow (femur) sections (scale bar, 50 μm).