RPI-1, a novel 2-indolinone RET tyrosine kinase inhibitor, has shown promising results in sporadic papillary thyroid carcinomas with frequent RET alterations in vivo.375 The therapeutic effect was quite immediate, and tumor proliferation was efficiently controlled, with the tumor weight reduced to 20% of the control group. The gene discussed is RET; the disease is thyroid gland papillary carcinoma.