The most aggressive bone tumours, such as osteosarcomas and chondrosarcomas, were consistently observed to be unreactive for LF; while the pattern of LF expression was mainly evident in the early phases of bone growth, suggesting an important role for LF as a bone growth regulator in the early phases of skeletal development, particularly in endochondral ossification (12,15). The gene discussed is LTF; the disease is chondrosarcoma.