YY1 and neoplasm: 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.