BST2 and breast cancer: Increased BST2 expression has been observed in multiple human cancers, including hematological tumors and solid tumors, especially in breast cancer, HCC, gastrointestinal cancer, and lung cancer (28) via activating signaling pathways, such as EGFR/AKT, NF-κB/ERK, and GRB2/DIM/caspase 3 (29–31).