In another study, ATM inhibitor (AZ31) also enhanced the antiproliferative effect in CRC cell lines (HCT15, HCT116, and RKO) and patient derived xenografts with the addition of topoisomerase I inhibitor (SN38), due to a cytostatic effect (increase in G2/M cell cycle arrest without apoptosis induction) [153]. This evidence concerns the gene ATM and colorectal carcinoma.