PSMC2 and breast carcinoma: To determine the importance of PSMC2 in breast cancer development, we silenced PSMC2 via lentivirus-mediated transferring of short hairpin RNAs (shRNAs) into two human breast cancer cell lines (MCF-7, MDA-MB-231), which expressed significantly higher PSMC2 than mammary epithelial cell line HBL-100.