DDIT4 and leukemia: Given that Hoxa6 was the most significantly downregulated Hoxa cluster gene in AE9a‐Ddit4−/− cells and had been demonstrated to induce malignant transformation of primary hematopoietic cells [30], we next investigated whether re‐expression of Hoxa6 could rescue the attenuated leukemia initiation potential caused by Ddit4 deletion.