In vitro and in vivo (orthotopic xenograft) results showed that hypoxic CAF-derived lactate, which provides metabolic coupling between CAFs and breast cancer cells, promoted breast cancer cell invasion by activating the TGF-β1/p38 MAPK/MMP2/9 signaling axis and fueling the mitochondrial activity in cancer cells 33. Here, MMP2 is linked to breast carcinoma.