A study reported that the secretion of TNF‐α by J2T12 cells (plasmacytoma J558 cell‐derived clone expressing TNF‐α) suppressed tumor growth in vivo when injected into the syngeneic BALB/c mice, whereas the inoculation with parental J558L cells resulted in the development of tumors, suggesting that the anti‐tumor activity of TNF‐α possibly via recruitment of inflammatory cells such as macrophages, neutrophils, and natural killer (NK) cells [54]. This evidence concerns the gene TNF and plasmacytoma.