TACSTD2 and cancer: Trophoblast cell surface antigen 2 (Trop2), a transmembrane glycoprotein overexpressed in various cancers (e.g., triple-negative breast cancer [TNBC]12, non-small cell lung cancer13, urothelial carcinoma [UC]14), promotes tumor proliferation, metastasis, and drug resistance via ERK15, PI3K/AKT16, and other signaling pathways17, correlating with poor prognosis.18