Anti-Phospho-B23/NPM1 (S4) Antibody

NPM1 (Nucleophosmin/Nucleoplasmin family, member1), also known as NPM, nucleolar phosphoprotein B23 or numatrin, is a protein that in humans is encoded by the NPM1 gene. The NPM1 gene maps to chromosome 5q35. Chan et al. (1989) found that nucleophosmin is a nucleolar phosphoprotein that is more abundant in tumor cells than in normal resting cells. Stimulation of the growth of normal cells, e.g., mitogen activation of B lymphocytes, was accompanied by an increase in nucleophosmin protein level. They stated that nucleophosmin is likely involved in the assembly of ribosomal proteins into ribosomes. Electron microscopic study indicated that nucleophosmin is concentrated in the granular region of the nucleolus, where ribosome assembly occurs.