MAP2 (Microtubule-associated protein 2) is a member of the microtubule-associated protein family. These proteins are involved in microtubule assembly, essential for neurogenesis. They may be involved in controlling and supporting dentritic shape in developing neurons. In immunohistochemistry, MAP2 is a useful marker of neurons (glial precursor cells) and neuronal differentiation and shows cytoplasmic positivity. It is also used in the differential diagnosis of a number of diseases. For example, Hirschsprung’s disease is described by loss of MAP2 versus normal tissue. In ischemic stroke, it may be used to measure infarct volume. In neuroepithelial tumors, it distinguishes oligodendrogliomas and astrocytomas (positive) from dysembryoplastic tumors and the clear cell component of neurocytomas (negative). Finally, it may be a useful marker of prognosis in melanoma, as MAP2 positivity correlates with survival. References: Histopathology. 2015 May;66(6):824-35, PMID: 25123159; Epilepsy Res Treat. 2012; 2012: 624519, PMID: 22957233; Am J Pathol. 2005 Jun; 166(6): 1841–1850, PMID: 15920168; J Neurosci Methods. 2009 Sep 15;182(2):205-10, PMID: 19540877; J Neuropathol Exp Neurol. 2001 Oct;60(10):984-93, PMID: 11589429