ADORA2A and melanoma: It involves in colorectal cancer with high expressions of A2aR and PD-L1 associated with a poor prognosis [29], gastric cancer with increased A2AR expression associated with TNM stage, lymph node metastasis, distant metastasis and poor prognosis [30], breast cancer with activation of A2AR increased the proliferation and invasion ability [31], and melanoma with increased A2a and A2b level to benefit tumor proliferation [32].