SMAD7 and medullary thyroid gland carcinoma: The downstream target genes upregulated in aged MTC to Crlf1/Lifr pair functioned in inflammatory response (Abl1, Elmo1, Tpm1, Aldoa, Bhlhe40, Cirbp, Elf3, Smad7), cell cycle arrest (Btg2, Cdkn1a, Dusp1), cellular senescence (Cpeb4, Ier2), maintenance of stem cell quiescence (Hes1), cell death (Slc2a1, Zfp36, Dusp1), and innate immunity (Hk1, Irf9, Pim1) (Figure 4f).