This study showed the frequent overexpression of cdc25B in benign adenoma and carcinomas with low aggressive phenotypes and its decreased expression in those of very aggressive types, such as undifferentiated carcinoma and widely invasive follicular carcinoma, indicating that cdc25B expression is even inversely linked to the cell proliferating activity of thyroid neoplasms. The gene discussed is CDC25B; the disease is thyroid gland follicular carcinoma.