The percentage of cells in the subG1 peak observed in treated leukemia cells was higher respect to that observed in solid tumors cells, and the cleavage of PARP1 was evident after shorter time of exposure respect to melanoma and NSCLC cells, thus sustaining the evidence of a higher sensitivity of leukemia cells to IS20 and IS21 exposure, in agreement with the important role played by Bcl-2 in hematological malignancies 25. This evidence concerns the gene PARP1 and melanoma.