To determine the causal involvement of SLFN11 for PARPI sensitivity, we generated SLFN11-deleted (SLFN11-del) isogenic cell lines from four cell lines with high SLFN11 (prostate DU145, leukemia CCRF-CEM and MOLT4, and Ewing's sarcoma EW8) [23, 26] using CRISPR/Cas9 (Figure S1). Here, SLFN11 is linked to Ewing sarcoma.