To further confirm the effect of upregulated DDIT4 in AE9a leukemia cells by the endosteal region, we measured DDIT4 expression levels in AE9a cells co‐cultured with mouse OBC and BM MSC cells, as well as the mouse osteoblast cell line MC3T3‐E1 and MSC cell line OP9. The gene discussed is DDIT4; the disease is leukemia.