(G-H) .U-2-OS (Flp-In T-Rex) cells stably expressing CDKL5 were either mock treated or treated with 500 µM H2O2 for 30 min. Extracts were subjected to immunoprecipitation with antibodies against CDKL5 (G) or PAR (H) (or non-specific IgG as control). Precipitates, and input lysates, were analyzed by western blotting using the indicated antibodies. One of two independent experiments is shown 