PARP1 and breast carcinoma: For example, CARM1 interacts with and activates poly (ADP-ribose) polymerase 1 (PARP1) in an enzyme-independent manner during replication fork PARylation (31), and scRNA-seq analysis of MDA-MB231 breast cancer (BC) cells, following either Carm1 KO or CARM1i treatment, shows a distinct CARM1-KO population (not found in the inhibitor-treated cells) on a t-distributed stochastic neighbor embedding plot (32), suggesting that CARM1 loss may have a more profound effect on MDA-MB231 cell differentiation than CARM1i treatment.