RET and multiple endocrine neoplasia: Petrangolini et al (2006) tested the antitumor activity of RPI-1 (the indolinone RET tyrosinase kinase inhibitor) against large established subcutaneously thyroid tumor xenograft, a human medullary thyroid carcinoma harboring oncogenic MEN-2A-type RET mutation (MEN = multiply endocrine neoplasia).