P2RX7 and neoplasm: Although P2X7 receptor was originally described as a cytotoxic receptor promoting cell death, it has been demonstrated to activate proliferative pathways in the TME, such as Ca2+-dependent and independent ERK phosphorylation [103–105], mTOR-HIF1-α-VEGF [106], and PI3K-AKT [107, 108], as well as tumor metastasis [109].