EGFR and breast cancer: Therefore, various mouse models have been developed in CTCs capture studies, including syngeneic models (4T1 murine breast cancer cell line) 25, transgenic models (overexpressing EGFR) 26, and patient-derived xenografts (PDX, triple negative breast cancer patient-derived xenograft) 27, etc. In our study, we established a syngeneic model using murine cancer cells LLC1 and B16F10, which was chosen due to the ability to quickly metastasize to the lungs 15, 28.