Changes of the migratory activity of SH-SY5Y human neuroblastoma cells in response to PC-3 cell-conditioned medium. A and B: the migratory activity and directionality of migration was analyzed by means of the collagen-based three-dimensional assay utilizing time-lapse videomicroscopy. In A, the graph shows the mean value of three independent experiments (90 cells were analyzed per sample); in B, the graph shows the summary and mean value of four independent experiments (120 cells were analyzed). The arrow indicates the source of substances released by PC-3 cells. C: the images show the morphology of the SH-SY5Y cells. Mean values and standard deviation of the cells' lengths were calculated from sizing 120 cells per sample.