As COP1 is an E3 for several oncogenes and tumor suppressor proteins including c-Jun, ETS, β-Catenin, STAT3, MTA1, p27, 14-3-3σ, and C/EBPα [237,240], it is possible that it may depend on the cellular context whether high levels of COP1 are beneficial or detrimental for tumor patients. This evidence concerns the gene CDKN1B and neoplasm.