TGF-β suppresses tumorigenesis by promoting the differentiation of CSCs, downregulating the expression of ABCG2, which acts as a transmembrane transporter, inducing chemoresistance in CSCs, and decreasing the aldehyde dehydrogenase 1 (ALDH1)-positive population, which is capable of self-renewal, as well as of enhancing tumor initiation/progression through CSCs. Here, TGFB1 is linked to neoplasm.