Trop2 is a cell-surface glycoprotein overexpressed in a variety of late stage epithelial carcinomas with low to no expression in normal tissues. Some of the important roles that Trop2 plays in epithelial cancers have recently been revealed. Trop2 overexpression is associated with decreased patient survival as well as increased tumor aggressiveness and metastasis. Its overexpression in metastatic tissue makes it a very attractive and potential therapeutic target for late stage disease. This protein can transduce an intracellular calcium signal and contains a conserved phosphatidylinositol 4,5-bisphosphate (PIP(2)) binding motif as well as a serine phosphorylation site which interacts with protein kinase C. This protein has recently being found to be expressed in cells with stem-like properties which allude to a potential role in progenitor cell biology. Further understanding of the signaling pathways involved with this molecule and its important role in metastasis will shed new light on the mechanism of Trop2 overexpression in late stage disease and could result in the development of new therapies targeting this widely overexpressed oncogene.