Zheng et al., (2014) showed that TGF-β2 expression correlates with the BCSCs marker ALDH1 and represents a bad prognosis. Another study showed that CD49Fhigh and CD61high BCSCs are regulated by TGF-β in HER2+ breast cancer. (Lo et al., 2012). Recent studies have shown that TGF-β is capable to induce epithelial-mesenchymal transition, invasion, and lung metastasis and regulates apoptosis and resistance of BCSCs (Konge et al., 2018; Xu et al., 2018; Zhang et al., 2018; Katsuno et al., 2019; Yadav and Shankar, 2019; Tsubakihara et al., 2022). Here, ALDH1A1 is linked to breast cancer.