PARP1 and cancer: To further explore the involvement of the DDR proteins in the NORAD-mediated accumulation of γH2Ax we used siRNAs to KD (Figures 6A and 6B) two of the hits identified in the NORAD-associated proteome (LC-MS/MS experiment, Figure 3), namely PARP1 and CDK1, both proteins being extensively linked to cancer and DXR response.43