TDP1 and breast adenocarcinoma: We checked whether the substrate (a short hairpin oligonucleotide with non-nucleotide insertion) is cleaved in whole-cell extracts of various types of cells: TK6 (human lymphoblastoid), HEK293 (human embryonic kidney), HeLa (cervical cancer)–WT and TDP1-deficient (TDP1–/–), HCT116 (human colon carcinoma), and MCF-7 (human breast adenocarcinoma).