For instance, COP9 subunits such as CSN5 and CSN6 are excessively expressed in cancer cells such as myeloma, leukemia and glioblastoma, and CSN5 is associated with tumor suppressor genes such as p16, p27, p53 and Smad7 [42], [43], [44]. This evidence concerns the gene SMAD7 and glioblastoma.