The presence of CSCs in tumor tissues is the most common cause of therapeutic resistance and disease relapse [100], and STAT3 contributes to the maintenance of CSCs programs in cancer cells [101], so He and colleagues examined the expression of several stemness genes related to CSCs (Sox2, Oct4, Nanog, and c-Myc) as well as STAT3 signaling-related genes (p53, cyclin D1, Bcl-XL) in MDA-MB-231 cells. This evidence concerns the gene STAT3 and cancer.