Conversely, sgRNA against 53BP1, a known key modulator of chemoresistance in BRCA1-deficient tumours, were enriched specifically in the RPE1-hTERT TP53-/-;BRCA1-/- screen but not in the screens performed in BRCA2-deficient cells (Fig. 1c). This evidence concerns the gene TP53BP1 and neoplasm.