Therefore, this data indicated that the SN-38/erlotinib combination induced DNA damage response, like other members of the TOP1 and TOP2A poisons categories, supporting our previous data in Fig. 3B. We also confirmed a strong synergism between SN-38 and erlotinib in Eμ-Myc Cdkn2aArf−/− leukemia cells, used as a cell model in the signature assay (Fig. 6D, Fig. S6E–F). The gene discussed is TOP1; the disease is leukemia.