In summary, our results show (i) that ATM is frequently deleted in NB, and that deletion correlates with lower ATM expression, EFS and OS; (ii) that stable silencing of ATM by three different ATM shRNAs confers a growth advantage to three different NB cell lines in vitro and in vivo; (iii) that this effect is dependent on the extent of ATM silencing; (iv) that partial silencing of ATM is sufficient to observe such growth advantage, and (v) that this effect does not require the expression or the activity of MYCN. This evidence concerns the gene MYCN and neuroblastoma.