Actually, more and more genes with dual functions as a tumor suppressor or an oncogene in cancer development and progression have been identified, such as Yin Yang 1 (YY1) (Sarvagalla et al., 2019) and TGF-β (Xu J. et al., 2015), and what functions they play may depend on the type of tumors as well as the genotype and expression of some critical genes in tumor cells. This evidence concerns the gene YY1 and cancer.