Well-differentiated neoplasms are called neuroendocrine tumors (NETs) and can be either low grade (G1), with a mitotic count < 2 per 10 high power field (HPF) and < 3% Ki-67 index, or intermediate grade (G2), with mitotic activity of 2–20 per 10 HPF and 3–20% Ki-67 index. The gene discussed is MKI67; the disease is neuroendocrine neoplasm.