In the article titled “How to Treat a Signal? Current Basis for RET-Genotype-Oriented Choice of Kinase Inhibitors for the Treatment of Medullary Thyroid Cancer” [1], the following sentence should be added to the “Acknowledgments” section: This work was also supported by FEDER funds through Programa Operacional Factores de Competitividade (COMPETE) (FCOMP-01-0124-FEDER 011267).