Last, myeloid-derived suppressor cells (MDSCs) can promote tumor growth through immunological inhibition and non-immunological inhibition, in which immunosuppressive mediator ARG1 and inducible NO synthase (INOS) can decompose L-arginine into 1-ornithine and urea, NO and nitrite, an important mediator of the IL-2 pathway, resulting in T-cell expression incompetence (12, 13). The gene discussed is NOS2; the disease is neoplasm.