In addition, aldehyde dehydrogenase 1A1 (ALDH1A1) relies on its enzymatic activity to reduce intracellular pH in BC cells in order to increase TGF-β-activated kinase 1(TAK1) phosphorylation and activate NF-κB pathways, which then induces GM-CSF secretion, thereby inducing MDSCs amplification and promoting BC progression (27). Here, CSF2 is linked to breast cancer.