Otherwise, we showed that, unlike the well-described role of OPN in the modulation of tumor-progression features [5], in medullary thyroid cancer, overexpression of the OPNa variant is associated with cell differentiation and with good prognosis, and its expression was enhanced in non-invasive and small sized tumors, while its ectopic overexpression in medullary thyroid cancer cell lines induced lower proliferation and viability rates [80]. The gene discussed is SPP1; the disease is medullary thyroid gland carcinoma.