These tumors, however, when undergoing dedifferentiation become more aggressive and may show increased FDG uptake, and this is also the case in MTC as demonstrated by the immunoreactivity for KI-67 expression (KI-67 is a nuclear protein that is associated with cellular proliferation) in surgically removed lesions [3, 4]. The gene discussed is MKI67; the disease is medullary thyroid gland carcinoma.