We next investigated DLK1 expression in medullary and non-medullary thyroid carcinoma cells, isolated subpopulations of MTC cells expressing DLK1 (DLK1+) and those lacking DLK1 expression (DLK1−) and subjected them to a detailed characterization of their expression of stem cell markers. This evidence concerns the gene DLK1 and medullary thyroid gland carcinoma.