Conversely, the excessive buildup and alteration of ECM proteins that lead to tumor stiffening are triggered by the abnormal expression or secretion of pro‐fibrotic proteins and factors within the TME (Figure 3B).[33] Pro‐fibrotic elements present in the TME include TGF‐β, transforming growth factor α, platelet‐derived growth factor (PDGF), and epidermal growth factor (EGF). The gene discussed is TGFB1; the disease is neoplasm.