The E3 ubiquitin ligase MDM2 ligand nutlin-3 derivative and poly (ADP) ribose polymerase 1 (PARP1) ligand niraparib derivative PROTACs were used to target PARP1 degradation, thus causing human breast cancer cells MDA-MB-231 to undergo apoptosis [33]. The gene discussed is PARP1; the disease is breast carcinoma.