In search of reasons that RICH1 influencing the prognosis of breast cancer patients, we interrogated GSE7515, a gene set including expression profiles taken from 11 primary bulk tumor samples and 15 mammosphere samples derived from human breast tumors [21], and found that RICH1 was significantly down-regulated in cancer mammospheres (Fig. 2A). The gene discussed is ARHGAP17; the disease is breast cancer.