RBPJ (Recombination Signal Binding Protein For Immunoglobulin Kappa J Region): RBPJ is a key transcription factor in the Notch signalling pathway, which plays a critical role in regulating cell fate, differentiation, and development. Proper function of RBPJ is essential for tissue development and cell specialisation, while dysregulation of RBPJ and Notch signalling is associated with various diseases, including cancers and developmental disorders.