Tracking of individual cells (Fig. 1B) and quantification of total distance travelled (Fig. 1C) and the direct distance between the starting and finishing point of cell migration (Fig. 1D) showed that EphA2/EphA4 knockdown cells covered as much distance as control cells but they meandered back on themselves and in some cases re-entered the cancer cell population rather than continuing to migrate outwards into free space (Fig. 1G; supplementary material Movies 1 and 2). This evidence concerns the gene EPHA4 and cancer.