MYCN and breast cancer: The possibility of noncoding RNA regulation of ATM expression is supported by the report that miR-18a expression attenuated cellular repair of DNA DSBs by directly suppressing ATM in colorectal cancer and breast cancer.28, 29 Another study demonstrated that miR-421 suppressed ATM expression by targeting the 3'-untranslated region of ATM transcripts, and its expression was regulated by N-Myc in neuroblastoma.22 Post-translational modification of ATM could also have a role in regulating ATM kinase activity.