Indeed, dysregulation of different receptor-tyrosine kinase (RTK)-dependent signaling and proliferation pathways—such as the mitogen-activated protein kinase (MAPK), the phosphoinositide 3 kinase (PI3K), the Wingless/Integrated (WNT), the p53 and p73 pathways—are involved in the multistep tumorigenic process of thyroid cancer [25,26,27] (Figure 1). The gene discussed is PIK3CA; the disease is thyroid gland carcinoma.