However, even genetically diverse clones possess the stem cell markers CD133, CD15, A2B5, and CD44 (53), which suggests that despite the large amount of inter- and intra-tumor cell heterogeneity and the influence of the brain tumor microenvironment (54), at least some (if not all) stem cell markers remain consistent, thereby providing arguably one of the best targets for cancer therapy. The gene discussed is PROM1; the disease is cancer.