circRAD18-miR-516b regulates papillary thyroid cancer metabolism reprograming by the PDK1 pathway. (A) Glucose uptake rate was decreased after transfection with miR-516b mimics, which was reversed by supplement of PDK1. (B) Lactate production rate was reduced after overexpressing miR-516b mimics, which was reversed by PDK1 supplementation. (C,D) Introduction of miR-516b resulted in the decrease of PDK1 expression, detected by western blot analysis. **, P<0.01.