IL6 and neoplasm: Since their study only involved the administration of exogenous IL-6, we currently do not know whether the IL-6-induced NE trans-differentiation and LNCaP acquisition of castration resistance can also be endogenously triggered by intracellularly derived IL-6 within the cancer cells, or extracellularly from within the tumor microenvironment from other IL-6 producing tumor-associated cells, including macrophages [294].