The name ‘YBX’ was coined due to the ability of the YBX protein family to bind the Y box sequence on DNA, defined as 5′-CTGATTGG-3′. The YBX family of proteins has high sequence homology across different species. There are three members of the YBX family: YBX1, YBX2 and YBX3. As shown in Fig. 1, all members have structural commonalities as follows: an N-terminal alanine (A)- and proline (P)-rich domain (A/P domain), a central CSD and a C-terminal domain (CTD) consisting of alternating base/acid amino acid repeats. The A/P domain is thought to be important for the transcriptional activity of YBX1 and has also been shown to interact with tumor suppressor p53 to mediate p53-dependent transcription.