The TPX2 protein, also known as targeting protein for Xklp1, restricted expression proliferation associated protein p100, and differentially expressed in cancer and non-cancerous lung cells protein 2 (DIL2), is a 100 kD nuclear protein that contains two coiled-coil domains. The TPX2 protein is strictly associated with spindle pole and mitotic spindle during mitosis. In the G2/S position of the cell cycle, TPX2 is diffusely distributed throughout nucleus. TPX2 has been shown to be highly expressed in lung carcinomas cell lines, but not in normal lung tissues. TPX2 is thought to be required for the Ran-GTP dependent assembly of microtubules around chromosomes required to generate stable bipolar spindle with overlapping anti-parallel microtubule arrays and may also be involved in targeting Aurora-A kinase to the mitotic spindle. TPX2 has been shown to interact with a large number of proteins including serine/threonine protein kinase 6, ribosomal protein 6, Bop-1, alpha-tubulin, and nucleolin among others. TPX2 can be modified by phosphorylation on serine 738. The 18D5 monoclonal antibody recognizes human TPX2 and has been shown to be useful for Western blotting.