STAT1 and neoplasm: In models of breast cancer and lung cancer brain metastasis, tumor cells transfer 2’3’-cGAMP to astrocytes through tumor cell-astrocyte gap junctions, activating STING signaling in astrocytes, promoting the production of inflammatory cytokines, and subsequently activating STAT1 and NF-κB signaling in brain metastatic cancer cells, supporting tumor cell growth and chemotherapy resistance (111).