COPS5 and breast cancer: Jab1 is a tumour oncogene in a variety of human cancers46, 47 and has been shown to be a key molecule in nicotine‐induced lung cancer.48, 49 Remarkably, Csn5/Jab1 mediates stabilization of PD‐L1, which is crucial for breast cancer cells to escape immune surveillance via PD‐L1/PD‐1 interaction.