The authors established a 71-gene signature, indicative of MAPK pathway transcriptional activation, that permits to classify BRAFV600E- and RAS-mutated PTCs and to determine whether a given tumor, characterized by other less common or unknown alterations, resembles one of these two molecular subtypes, defining a BRAF-like or RAS-like signaling type, respectively. The gene discussed is BRAF; the disease is neoplasm.