AHNAK and neuroblastoma: Ahnak is a protein originally identified as a nuclear phosphoprotein in human neuroblastomas and skin epithelial cells.1, 2, 3 A protein of exceptionally large size, Ahnak can be divided into three structurally distinct regions: the amino-terminal 500 amino acids, a large central region of about 4388 amino acids composed of 36 repeat units and the carboxyl-terminal 1003 amino acids.