TGFB1 and neoplasm: Conversely, HER2‐negative tumors often exhibit low Ki‐67 expression due to poor blood supply and hypoxic conditions that further activate tumor signaling pathways (such as the HIF‐1α pathway), leading to the activation of fibrogenic factors such as TGF‐β, promoting the transformation of fibroblasts and increasing tissue stiffness through the synthesis of large amounts of collagen [29].