ATR and neoplasm: Overall, based on our present results we suggest that CuET (DSF/copper) evokes and/or exacerbates replication stress in tumor cells while concomitantly precluding the ATR-mediated pro-survival response to such stress, thereby collectively creating a toxic scenario (understandably more severe in BRCA1/2-defective cells) reminiscent of ‘killing two birds with one stone.’