Y-box-binding protein (YBX1), which belongs to a family of cold-shock proteins, is multifunctional and appears to regulate gene expression at both the transcriptional and posttranscriptional levels. The transcriptional targets for YBX1 include genes associated with cell death, cell-death-associated receptors, and tumor-suppression. YBX1 also upregulates genes associated with cell proliferation. YBX1 has been also shown to play an important role in inducing drug resistance in tumor cells. YBX1 binds RNAs in a sequence-specific manner, interacts with splicing factors, and plays important roles in mRNA splicing and translation. Recent studies have suggested that the efficient stimulation of eIF4F activity by poly (A)-binding protein (PABP) is mediated by competition between YBX1 and eIF4G for mRNA binding.