RET and medullary thyroid gland carcinoma: Verbeek and coworkers set out to compare the efficiency of four recently developed TK inhibitors, XL184, Vandetanib, Sunitinib and Axitinib, using three cell lines: the first derived from sporadic MTC expressing a C634W RET mutation, the second derived from metastatic sporadic MTC expressing a M918T RET mutation.