COP9 Sygnalosome ( CONSTITUTIVE PHOTOMORPHOGENIC 9) referred more often abbreviated as CSN ( COP9 signalosome called ) is a multiprotein complex nuclear commonly occurring Eucariotes . The results of many diverse studies have shown CSN participate in a wide range of vital processes , such as photomorhogenesis , regulation of cell cycle or cell differentiation . Increasingly complex COP9 signalosome is associated with the control of the ubiquitin mediated protein degradation .