A 28-year-old woman presents with a 2-week history of gum bleeding, epistaxis, and petechiae. Laboratory studies show pancytopenia, prolonged PT/PTT, fibrinogen 80 mg/dL, and D-dimer >10 μg/mL. Bone marrow examination reveals the abnormal cells marked **A** in the diagram — hypergranular promyelocytes with bundles of Auer rods (faggot cells). Which of the following best explains the molecular pathogenesis of this disease?