Rabbit Anti-Human NPM1 monoclonal antibody for IHC-P, FC. Nucleophosmin (NPM) is a nucleolar protein for regulating ribosome biosynthesis and centrosome duplication. The NPM gene is frequently rearranged in various types of lymphomas such as anaplastic lymphoma kinase (ALK) . A C-terminal mutation occurs in acute myelogenous leukemia (AML) and prevents localization to the nucleolus, resulting in cytoplasmic distribution. NPM is frequently overexpressed in diverse solid tumors such as carcinoma of the lung and breast, colon, prostate, stomach, lymphoid and myeloid tumors.