NAMPT and fibrosarcoma: Visfatin induces malignancy through signaling pathways that contain Rat sarcoma virus (Ras, it belongs to the G‐Small family of proteins), rapidly accelerated fibrosarcoma (Raf), mitogen‐activated protein kinase kinase (MEK1/2), extracellular signal‐regulated kinase (ERK), phosphoinositide 3‐kinase (PI3K), AKT serine/threonine kinase (Akt), and the nuclear factor‐ κB (NF‐κB).