To investigate the role of RICH1 in BCSCs, breast epithelial cell MCF10A with RICH1 knockdown (MCF10A-shRICH1-1 and MCF10A-shRICH1-2), and breast cancer cells SUM159 and BT549 with RICH1 overexpression (SUM159-RICH1 and BT549-RICH1) were established using RICH1-targeted lentivirus (Fig. 3A), followed by flow cytometry analysis of CSC contents in these cell lines. This evidence concerns the gene ARHGAP17 and breast cancer.