Guanine nucleotide-binding protein-like 3, also known as nucleostemin, is a protein that in humans is encoded by the GNL3 gene. [4] [5] [6] It is found within the nucleolus that binds p53. [7] Nucleostemin regulates the cell cycle and affects cell differentiation, decreasing in amount as this differentiation progresses. [7] It is a marker for many stem cells and cancer cells. [8]