FST and breast cancer: To the best of our knowledge, it is the first report that CAF-secreted Activin A has the ability to reduce the sensitivity of cancer cells to ixazomib; the presence of FST reversed this phenomenon, suggesting that targeting Activin A secreted by CAFs is a therapeutic target with which to overcome ixazomib resistance in MCF7 cells, or that ixazomib may be used to treat breast cancer patients with low expression levels of INHBA in CAFs.