Fig. 3
From: Natural killer group 2D receptor and its ligands in cancer immune escape
NKG2D-mediated tumor evasion. PGE2 binds to EP2/4 and inhibits NKG2D transcription via the AC/cAMP/PKA pathway. Kynurenine inhibits NKG2D transcription via the JNK pathway. Tregs and MDSCs secrete cytokines, such as TGF-β, and inhibit NKG2D expression. The tumor itself can also express NKG2D receptor, which binds to NKG2DL on adjacent tumor cells, activates the PI3K/AKT/mTOR signaling pathway, and promotes tumor proliferation