CDKN1B and tumor of parathyroid gland: The expression levels of CDC73 and CDKN1B/p27, interacting with molecules involved in WNT/β-catenin and parathyroid-specific pathways and modulated by epigenetic mechanisms like lncRNAs and histone-related methylation, may determine the heterogeneity of the clinical features of parathyroid tumors.