A, DCFH-DA fluorescence was used to measure ROS by flow cytometry in thyroid cancer cells treated with PXD101 for 16 hours. Increasing doses of PXD101 produced more ROS in WRO82-1 and 8505C, but this effect was not observed in BHP7-13. B, two cell lines represent the ability of PXD101 to accumulate ROS. C, Immunoblot shows PXD101 repressed p-ERK1/2 (Thr202/Tyr204), p-AKT (Ser473), p-4E-BP1 (Thr37/46) and p-S6 ribosomal protein (Ser235/236) in 8505C. The inhibitory effects were not observed when low dose of PXD101 (0.625 µmol/L) applied in BHP7-13 and WRO82-1. D, increasing doses of PXD101 enhanced degradation of KU70, KU80 and RAD51, and enhanced expression of p-H2AX (Ser139), RAD52 and ERCC1 in BHP7-13, WRO82-1 and 8505C.