ADORA2A and gastric cancer: A2aR expression is enhanced on metastatic gastric cancer MKN45 cells and adenosine interaction with adenosine receptor A2a provokes the invasiveness and migration of these cells and eventually leads to metastasis through augmenting the PI3K–AKT–mTOR signaling and the expression of MMP-2, MMP-7, MMP-9, and MMP-13 [112].