S100A4 and leukemia: Moreover, while more leukemia cells migrated after treatment with BM-MSC-exos than in the NC group (P < 0.05), the migration ability of leukemia cells with S100A4 knockdown and BM-MSC-exos treatment was weaker than that of leukemia cells with BM-MSC-exos treatment alone (P < 0.05).