FOP, also known as FGFR1OP (FGFR1 oncogene partner), is a 399 amino acid protein that localizes to the centrosome and contains one LisH domain. Expressed ubiquitously with highest expression in kidney, heart, muscle, colon, liver, testis and pancreas, FOP functions as a homodimer that interacts with EB1 and CEP350 and is essential for anchoring microtubules to centrosomes. Chromosomal aberrations that involve the FOP gene are associated with the pathogenesis of stem cell myeloproliferative disorder (MPD), a condition that is characterized by eosinophilia and myeloid hyperplasia and ultimately leads to acute myeloid leukemia. FOP is expressed as multiple isoforms that are produced by alternative splicing events.