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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: Semin Oncol. 2010 Oct;37(5):473–484. doi: 10.1053/j.seminoncol.2010.09.001

Figure 1. CTLA-4 is a negative regulator of T cell activation.

Figure 1

Conventional T cells are activated by engagement of MHC (signal 1) and B7 (signal 2). Upon activation, T cells express CTLA-4 on the cell surface. CTLA-4 engagement with B7 inhibits T cell activation. Antibody blockade of CTLA-4 interaction with B7 prevents this inhibitory signal.