EGF and thyroid cancer: TGF-β1 and epidermal growth factor- (EGF-) like ligands have opposite roles in different stages of thyroid cancer growth: on one hand, they act as tumor suppressors through inhibiting the proliferation of thyroid cells and regulating the formation of extracellular matrix [27, 28]; on the other hand, they can promote angiogenesis in advanced stage of thyroid cancer [29].