Suppressed interferon regulatory factor 8 (IRF8) contributes to cell proliferation and leukemogenesis of T‐cell acute lymphoblastic leukemia (T‐ALL) via transcriptional regulation of PIK3R5 and activation of phosphatidylinositol 3‐kinase (PI3K)/AKT pathway. The gene discussed is PIK3R5; the disease is acute lymphoblastic leukemia.