Targeting protein for Xklp2 is a protein that in humans is encoded by the TPX2 gene. It is one of the many spindle assembly factors that play a key role in inducing microtubule assembly and growth during M phase. Because of its integral role in microtubule assembly and therefore mitosis, TPX2 is found to be overexpressed in different types of human cancers including hepatocellular carcinoma (HCC), medullary thyroid cancer, bladder carcinoma, and estrogen receptor-positive metastatic breast cancer and contributes to tumor growth and metastasis. As a result, TPX2 has recently been a topic of interest for learning more about the relationship between mitotic errors and tumorigenesis, along with novel cancer therapies.