HBEGF and thyroid gland undifferentiated (anaplastic) carcinoma: Although additional studies should be carried out to establish the functional interaction between HB-EGF and HER4 as well as HER1 in thyroid carcinoma cells, these results can serve as a foundation for the development of novel therapeutic strategies including molecular targeted therapy for HB-EGF and EGFR signaling in undifferentiated thyroid carcinomas.