Cancer cell culture, coloured scanning electron micrograph (SEM). The cancer cells (pink) have been grown on a support medium, allowing them to show their ability to migrate (metastasise). This is the process by which cancer spreads in the body. These are medulloblastoma cancer cells from the cancer cell line UW228. Medulloblastoma is a type of brain cancer. It is most common in children and tends to grow rapidly, spreading across the brain and spinal cord.