IL6 and metastatic malignant neoplasm: Based on the emerging relevance of tumor–stromal cells crosstalk and the characterization data of the CAF secretion profile [11], we focused on cellular responses induced by cytokines and chemokines, such as IL-6 and IL-8, which promote cancer stemness, as well as TGF-β and CXCL-16, which are involved in metastatic cancer cells spreading [42,43].