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. Author manuscript; available in PMC: 2018 May 11.
Published in final edited form as: Curr Opin Immunol. 2013 Apr 9;25(3):381–388. doi: 10.1016/j.coi.2013.03.003

Figure 1. PD-1 inhibits TCR/CD28 signaling.

Figure 1

Upon engagement with PD-L1 or PD-L2, PD-1 is phosphorylated at both thyrosine containing motifs ITIM and ITSM. The phosphatase SHP2 (and possible SHP1 as well) is recruited to phosphorylated ITSM. SHP2 dephosphorylates phosphatidylinositol-3-kinase (PI3K) and ZAP70/CD3ζ, ultimately attenuating TCR/CD28 signaling and T cell activation [9–11].