Nucleolin is a multifunctional nucleolar protein that plays a crucial role in various cellular processes such as ribosome biogenesis, RNA metabolism, and cell proliferation. It is located predominantly in the nucleolus but can also be found in the nucleoplasm and cytoplasm. Nucleolin has been implicated in several diseases, including cancer, where its expression is often dysregulated and has been linked to tumor progression and metastasis. Research on nucleolin aims to further understand its functions, regulation, and potential clinical implications in various diseases.