Fig. 2: Regorafenib induces neuroblastoma cell apoptosis.

SK-N-AS, IMR-32, NGP and SK-N-SH neuroblastoma cells were treated with 2.5, 5 or 10 µM regorafenib for 72 h, and were evaluated using a caspase activity assay. Images were obtained and were analysed using the IncuCyte Zoom^TM, with individual green dots representing cells with increased caspase activity. a Images of untreated cells and of cells treated with 10 μM regorafenib for 72 h are shown. Average green dot counts per field were normalised to control cells, and fold change was determined by comparing average green object counts in treated cells with average counts in untreated cells. The final results were compared using Student’s t tests (*p < 0.05, **p < 0.01, ***p < 0.001). b The average percentage of apoptotic cells (as measured by green object count) compared with the total cell number determined by phase-contract imaging. Changes in the numbers of individual cells treated with regorafenib with increased caspase activity were normalised to controls and compared with untreated cells. The final results were compared using Student’s t tests (*p < 0.05, **p < 0.00001). c SK-N-SH neuroblastoma cells were treated with 5 µM or 10 µM regorafenib for 48 or 72 h, and treated cells were lysed and analysed by western blot for total and cleaved PARP.