CXCL12 and cancer: These adaptative changes are further supported by proteomic and genomic alterations.157 Interactions between the stroma and cancer cells can also drive cancer progression by secreting growth factors and signaling molecules (e.g., transforming growth factor-β (TGF-β), stromal-derived factor (SDF-1), etc.).158 Hypoxia also promotes the epithelial–mesenchymal transition (EMT) that plays an important role in metastasis.