Aurora A (also known as Aurora 2) is a serine/threonine kinase with a molecular weight of approximately 46 kD. This kinase is highly expressed in the thymus and some tumors and is also expressed in other tissues including the lung, testis, colon, placenta, and fetal liver. Aurora A localizes in the midzone or central spindle in late anaphase and is concentrated in the midbody in telophase and during cytokinesis. This kinase is believed to act in cell cycle regulation during anaphase and/or telophase at centrosome/spindle pole during chromosome segregation. Aurora A has been shown to regulate cleavage of polar spindle microtubules at the onset of cytokinesis during mitosis. Defects in Aurora A cause numerous centrosome aberrations including aneuploidy (genetic variant with amino acid substitution F31I). Aurora A expression is cell cycle regulated, low in G1/S, and accumulating in G2/M. Expression is upregulated in cancer cells during M phase. Phosphorylation by PKA has been shown to regulate function. Aurora A phosphorylation has been reported on Thr 288. This kinase associates with the centrosome and mitotic spindles, NM23-H1, protein phosphatase type I, and co-localizes with gamma-tubulin. The Phe 31 variant has been shown to interact with the E2 ubiquitin-conjugating enzyme, UBE2N. The Poly6187 antibody has been shown to react with phosphorylated human Aurora A. This antibody has weak avidity for Aurora B in immunofluorescence. To minimizeAurora B cross-reactivity, it is recommended that the reagent be titrated and more stringent wash conditions be employed.