TP53 and Ewing sarcoma: We also mention that the same miRNA may exert opposite functions in different tumors: for instance, the overexpression of miR-125b that down-regulates p53 in colorectal cancers [87], seems to induce cell cycle arrest and apoptosis in Ewing sarcoma cells, possibly by p53 activation through down-regulation of PI3K and phospho-AKT [88].