USP5 and neoplasm: Several recent studies have implicated the involvement of USP5 in the regulation of tumor cell growth [51, 52], which may account for the observation of some Leon depleted cells are smaller than control neighboring cells in Drosophila. Moreover, in non-small cell lung cancer (NSCLC) cells, USP5 enhances the protein stability of cyclin D1 and PD-L1, and promotes NSCLC cell proliferation and progression [53, 54].