Our previous work in mice identified Cux1 as a potential T-cell leukemia tumor suppressor gene, with Cux1-deficient tumors exhibiting increased PI3K signaling, due to loss of CUX1-regulated expression of the gene encoding phosphoinositide 3-kinase interacting protein 1 (PIK3IP1)—a PI3K inhibitor18,23. The gene discussed is CUX1; the disease is leukemia.