microRNAs (miRNAs) are genes involved in normal development and cancer. They inhibit gene expression through interaction with 3'-untranslated regions of messenger RNAs, and are thought to control the expression of a large proportion of the protein-coding genome. However, it is becoming apparent that RNA-binding proteins (RBPs) control the biogenesis of miRNAs, their activity and stability. This indicates the existence of interplay between RBPs and miRNAs that affects gene expression and processes ranging from development, maintenance of stem cell phenotype and stress responses. Although miRNAs are prominent factors in cancer, little is known about how RBPs affect their cancerous function.