AKT1 and thyroid gland papillary carcinoma: Metformin induced p-AKT in TPC1 and human follicular thyroid cancer cells (FTC236) via PI3K/AKT signaling activated by rearrangement in the transformation/papillary thyroid carcinomas gene (RET/PTEC) and phosphatase and tensin homolog (PTEN) mutation, respectively.