The receptor, tyrosine kinase c-Ret, has been found to be an oncogenic mutation in patients with multiple endocrine tumors and cancer syndromes with familial medullary thyroid carcinoma, and DOK5 can be directly associated with Y1062 of c-Ret, thereby enhancing the effect of c-Ret [3]. Here, DOK5 is linked to familial medullary thyroid carcinoma.