Cell survival assay showed that PAXX deficiency increased sensitivity to most of these stimuli except for CPT (33), the inhibitor of DNA topoisomerase I. Human colon cancer cell line HCT116 in which PAXX was depleted using CRISPR-Cas9 technology or osteosarcoma cell line U2OS that was treated with small interfering RNA (siRNA) against PAXX also showed hypersensitivity to IR treatment and delayed γH2AX foci resolution (43). This evidence concerns the gene PAXX and osteosarcoma.