RET and medullary thyroid gland carcinoma: This has been clearly demonstrated in medullary thyroid carcinoma, in which a genetic rearrangement affecting the gene encoding the RET protein tyrosine kinase, which appears early and is sufficient and necessary for tumor development, generates a transcriptional program in the tumor cell similar to that which appears in the development of inflammation, with the transcription of growth factors, chemokines and proteases, which favor invasion and metastasis [223,224].