Recent miRNA studies on human leukemia cell lines, namely K562 cells, differentiated to megakaryocytes or erythrocytes and HL60 cells differentiated to macrophages or monocytes provided compelling evidence for an up-regulation of miR-24 that leads to a down-regulation of its target H2AX, consequently suppressing efficient DNA repair (Lal et al., 2009). This evidence concerns the gene H2AX and leukemia.