THRB and metastatic malignant neoplasm: In the light of complex secondary structures of low copy number TRβ1 5’UTRs including variant F [23] and evidence for selective protein synthesis of some alternatively spliced mRNA variants in oxygen deprived tumors or metastatic cancers [13, 16], it has been suggested that the sequence diversification of TRβ1 5’UTRs could play an important role in controlling THRB gene expression and this may influence tumor progression [23, 44].