Antigen specific T cell responses are required for maintaining stable diseases. (A) Eighteen days after RT, CD8+ and CD4+ T cells were depleted in stable B16-SIY tumor. *p=0.016, n=8. V0 represents the tumor volume at the day of starting antibody treatment and V represents the tumor volume after antibody treatment. (B) Thirty five days after RT, mice with stable TUBO tumor were selected and depleted of CD8 or CD4 cells. *P=0.015, n=8. (C) Unlike in WT host, TUBO tumors in SCID mice could not reach equilibrium. Mice were treated as Fig. 1A. n=10. (D) TUBO tumors in BALB-neuT can be induced into equilibrium by RT. Tumors were irradiated with 30Gy 15 days later. Tumors in individual mouse were shown. One of two (A, C, D) or three (B) representative experiments is shown, respectively.