They not only possess the ability to defend against pathogens and cancer cells but are also activated by various stimuli or cytokines secreted by immune cells; this enables macrophages to secrete various physiologically active substances and pro‐inflammatory cytokines, such as nitric oxide (NO), tumor necrosis factor (TNF‐α), interleukin (IL)‐1β, and IL‐6, to maximize the immune response (Scheller, Chalaris, Schmidt‐Arras, & Rose‐John, 2011; Valledor, Comalada, Santamaría‐Babi, Lloberas, & Celada, 2010). Here, TNF is linked to cancer.