CSDE1 (Cold shock domain-containing protein E1), also known as UNR (upstream of N-ras), is an RNA-binding protein involved in the regulation of messenger RNA stability and internal initiation of translation. It is required for internal initiation of translation of human rhinovirus RNA. UNR may be involved in translationally coupled mRNA turnover. Reduced expression of UNR impairs proliferation and differentiation of erythroid blasts. Recent study found that UNR acts as a positive or negative regulator of cell death, depending on the cell type, suggesteing manipulation of UNR level may constitute a specific approach to sensitize cancer cells to anticancer treatments.