question: What is the role of the constitutive photomorphogenesis 9 signalosome (CSN)?
answer: The constitutive photomorphogenesis 9 (COP9) signalosome (CSN) is a protein complex involved in the ubiquitin proteasome system and plays a role in regulating the degradation of polyubiquitinated proteins. The mammalian CSN is also involved in embryonic development, in cancer and the DNA damage response, whereas in plants CSN plays a role in innate immunity.