Trophoblast cell surface antigen 2 (TROP2), also known as tumor-associated calcium signal transducer 2 (TACSTD2), is a transmembrane glycoprotein and epithelial cell adhesion molecule (EpCAM) family member.{62950,62951} It is composed of a signal peptide, an extracellular domain, which contains a cysteine-rich domain, thyroglobulin type-I domain, putative EGF-like domain, and cysteine-poor domain, a transmembrane domain, and a cytoplasmic tail, which contains a HIKE domain, PKC phosphorylation site, and a PtdIns-(4,5)-P2 (PIP2) binding site. Tacstd2 is expressed in trophoblasts, kidney, lung, ovary, and testis and localizes to the cell membrane and cytoplasm.{62952,62953,62950,62954} TROP2 is involved in embryonic and fetal development, cell adhesion, migration, and proliferation and interacts with ?-catenin, ?5?1 integrin, and insulin-like growth factor 1 (IGF-1), among others.{62950} TROP2 is highly expressed in various cancer tissues, and overexpression of TACSTD2 increases metastasis in a colon cancer mouse xenograft model.{62950,62955} Loss-of-function mutations in TACSTD2 result in gelatinous drop-like corneal dystrophy.{62954} Formulations containing an antibody-drug conjugate targeting TROP2 have been used in the treatment of triple-negative breast cancer (TNBC) and urothelial cancer. Cayman’s TROP2 Rabbit Monoclonal Antibody (Clone 046) can be used for immunohistochemistry (IHC; paraffin).