SMAD4 and thyroid gland papillary carcinoma: MiR-146b-5p was reported to promote the migration and invasion of papillary thyroid cancer cells via downregulating ZNRF3 and upregulating Wnt/catenin signaling pathway, and to promote thyroid follicular cell growth via downregulating TGF- β pathway by binding to the 3′-untranslated region of SMAD4 (Chou, Liu & Kang, 2017; Deng et al., 2015; Geraldo, Yamashita & Kimura, 2012).