To prove the metastasis-forming ability of cCSCs and their clonal proliferative potential, a tumorsphere-formation assay was successfully performed and it was able to show positive stainings for EpCAM + , CD24 low, CD44 + , CD133 + , and ALDH1 in spherical colonies formed from a single cancer stem cell (Fig. 2). The gene discussed is ALDH1A1; the disease is cancer.