APEX1 and cancer: Primarily, we confirmed previous results obtained by our research group evaluating Ref-1 expression in MSTO-211H mesothelioma cells compared to Met-5A human mesothelial cells and NSCLC A549 cells, used as positive controls of Ref-1 overexpression in cancer; our results clearly demonstrated significant Ref-1 overexpression in MSTO-211H toward Met-5A cells (Figure 1A,B).