MSY2 and YB-2 (MSY3,4) belong to the Y-box family of multifunctional proteins that regulate both transcription and translation (1–3). Y-box proteins interact with a wide variety of nucleic acid structures to act as transcription factors and mRNA masking proteins (1). The modular structure of Y-box proteins includes a highly conserved N-terminal cold-shock domain (CSD, equivalent to the bacterial cold-shock proteins) and four basic C-terminal domains containing arginine clusters and aromatic residues (4). MSY2 is expressed in testis and ovary where it may repress translation of parental mRNA (5,6). The gene encoding human MSY2 maps to chromosome 17p11.2-13.1 (5). YB-2 (MSY3,4 in mouse) is also known as DNA binding protein A and is highly expressed in the testis, heart and muscle (7,8). MSY2 and YB-2 bind to the consensus sequence 5'-UCCAUCA-3' contained in the Y-box element (9).