CTCF is a zinc finger protein that binds to specific DNA sequences known as CTCF-binding sites. It functions as a transcriptional regulator, chromatin organizer, and enhancer blocker. CTCF can either activate or repress gene expression, depending on the context and interacting proteins. It can bind to promoters, enhancers, and silencers to regulate transcription. CTCF is involved in the formation of chromatin loops and topologically associating domains (TADs). These loops and domains help organize the genome into functional units and regulate gene expression. CTCF can block the interaction between enhancers and promoters, preventing enhancer-mediated gene activation. This function is important for maintaining tissue-specific gene expression patterns. Mutations or abnormal expression of CTCF have been linked to various diseases, including cancer, developmental disorders, and neurological diseases.