SPON1 and osteosarcoma: The 7 markers used in this model correspond to amplicons contained within the gene or promoter region of ANKRD33B, CHST2, SPON1, PPP2R5C, KCNG2, KIAA1522 and TH2LCRR. Consistent with the neuronal theme identified in the gene set enrichment analysis, SPON1 is a cell-surface adhesion molecule involved in sensory neuron attachment; its expression has been associated with metastatic progression in osteosarcomas [21].