In a mouse model of 3′-methylcholanthrene (MCA) induced sarcomas, the equilibrium or dormant state of tumor, which was characterized by a combination of decreased proliferation and increased apoptosis of tumor cells, was maintained by adaptive immune components, including CD4/CD8 T cells, interferon (IFN)-γ and interleukin (IL)-12 (17). Here, CD4 is linked to sarcoma.