PIK3CA and thyroid cancer, nonmedullary, 2: Like the MAP kinase pathway aberrantly activated by the BRAF mutation that plays a fundamental role in thyroid tumorigenesis, particularly in PTC [5], aberrantly activated RAS/PI3K/AKT pathway (PI3K pathway) is another fundamental mechanism in thyroid tumorigenesis, particularly in FTC and ATC [6, 7].