Cell proliferation depends on the accurate and efficient processing of RNA transcripts to couple transcriptional and translational machineries to provide for rapid biomass accumulation. The 5' cap structure of RNA polymerase II transcripts and the nuclear cap binding complex (CBC) are important contributors to an array of post-transcriptional RNA processing events. This thesis identifies the protein Ars2 as a component of the nuclear CBC that is selectively expressed in proliferating cells. Ars2 is required for cell proliferation in vitro and in vivo in mammalian organisms. Ars2 serves as a biochemical bridge between the nuclear CBC and the microRNA processing machinery that contributes to gene silencing in proliferating cells. Furthermore, this thesis identifies Ars2 as an snRNA-binding protein that is required for the maintenance of snRNA levels. This work highlights the role of Ars2 as an RNA binding protein that has the potential to globally regulate various post-transcriptional maturation events to promote efficient gene expression in proliferating cells.