SPP1 and differentiated thyroid carcinoma: In terms of the regulation of OPN expression, in papillary thyroid carcinomas, an association was found between the OPN-encoding gene SPP1 and the high-mobility group proteins AT-hook 1b (HMGA1b) and chromobox homolog 7 (CBX7), which upregulated and downregulated SPP1 expression, respectively, through specifically binding to its promoter [78].