PML/RARα transgenic murine APL models mimic this notion well, in which PML/RARα only does not induce leukemia (PML/RARα transgenic preleukemic mice) and additional secondary events cooperating with PML/RARα promote APL development (PML/RARα transgenic APL mice). The gene discussed is PML; the disease is acute promyelocytic leukemia.