INHBA and cancer: To investigate the effect of activin A on the secretome and matrisome of fibroblasts and the relevance of these secreted factors for cancer cell behavior, we generated human primary fibroblasts with DOX‐inducible overexpression of activin A (Fb Act), thus mimicking the activin A autoinduction seen upon exposure of fibroblasts to exogenous activin A. We selected clones, which show a fourfold to fivefold INHBA overexpression that is comparable to the overexpression seen in response to activin A treatment (Fig 3A and B).