CD200 and acute myeloid leukemia: Thus, the bone marrow microenvironments of MDS → OL (AML‐MRC) and de novo AML were found to be completely different from the normal functions of niche cells.31 In MDS bone marrow, CD34‐positive/c‐kit‐positive cells are generally located in proximity to CXCL12‐positive cells and express the BCL‐2 protein, resulting in the suppression of apoptosis.