Despite a series of success such as obtaining the monoclonal antibody recognizing the glycosylated epitope of CD133 in 1997 [27] and human CD133 independent of glycosylation in 2005 [28], subsequently the first detection of CD133 expression in gastric cancer tissue of 97 cases in 2010 [29], and following basic and clinical studies, there are still some controversies between the overexpression and clinical significance of CD133 in gastric cancer. The gene discussed is PROM1; the disease is gastric cancer.