2.4. Establishment of PRMT1 Knockdown Cell Lines

PRMT1 knockdown cell lines were established as described previously [15]. Briefly, PRMT1 shRNAs were cloned into the pLKO.1 vector and control shRNA was a hairpin RNA designed against GFP. HEK293T cells were cotransfected with lentiviral constructs (psPAX2 and pMD2.G) and the indicated pLKO.1 plasmid. MCF7 and MDA-MB-231 cells were infected using lentivirus expressing shPRMT1 or shGFP. Infected cells were selected with puromycin. Then, Western blotting analysis was performed to determine the expression levels of PRMT1 in multiple monoclonal cultures. The primers are listed in Supplementary Table S1.