Upregulated cancer genes in both canine and human MTC transcriptomes included FOXA1, RET, ETV4, and DUSP4. Moreover, four of the top ten DEGs identified in another study of human MTCs15, CALCA, CALCB, GFRA4, and SEMA3E, were also significantly upregulated in canine MTCs (Supplementary Fig. 2). Here, GFRA4 is linked to medullary thyroid gland carcinoma.