To produce an abnormal ECM that would mimic the breast tumor matrix composition (adECM), we used TGF‐β1‐activated fibroblasts (adECM), which adopt a CAF‐like phenotype in vitro.[20] Untreated fibroblasts were used to obtain the normal ECM counterpart (ndECM). Here, TGFB1 is linked to breast neoplasm.