MYC and leukemia: Although c-Myc overexpression is known to induce apoptosis under certain circumstances31,32,38, elevation of c-Myc itself is not sufficient to induce the killing effect in the leukemia model used in our study whereas Sox2 or Klf4 alone, or the synergistic effect when both factors are combined, is sufficient to selectively eliminate MLL-AF9-OSKM cells.