Migrating Ewing sarcoma cancer cell, confocal light micrograph. A fluorescent marker has been used to highlight actin filaments (purple). Actin filaments make up part of the cytoskeleton, which maintains the cells shape, allows some cellular mobility and is involved in intracellular transport. Ewing, or Ewings, sarcoma is a rare malignant (cancerous) tumour of bone tissue. It is most common in teenagers and young adults and is most likely to occur in the pelvis and long bones. Very rarely it can occur in the soft tissues around a bone. Magnification: x630 when printed at 10cm.