New tricks for an old dog: ribosome biogenesis contributes to stem cell homeostasis.

Although considered a 'house-keeping' function, ribosome biogenesis is regulated differently between cells and can be modulated in a cell-type-specific manner. These differences are required to generate specialized ribosomes that contribute to the translational control of gene expression by selecting mRNA subsets to be translated. Thus, differences in ribosome biogenesis between stem and differentiated cells indirectly contribute to determine cell identity. The concept of the existence of stem cell-specific mechanisms of ribosome biogenesis has progressed from an attractive theory to a useful working model with important implications for basic and medical research.