Nucleolin is a multi-functional protein that is one of the major components of the nucleoli. It plays an essential role in various steps of ribosome biogenesis including rRNA synthesis, processing of pre-rRNA, pre-ribosomal RNA assembly, and transport of ribosomal proteins out of the nucleus. While the main function of nucleolin is ribosome biogenesis, it plays an important role in various other nuclear activities. Down regulation of nucleolin leads to increased expression of p53, defects in genome duplication, and a delay at prometaphase during mitosis leading to cell cycle arrest.
