USP6 and neoplasm: Several lines of evidence led us to speculate that CD147 is one of the potential candidate cargoes; first, elevated expression of CD147 as well as TRE17 increases production of MMPs, and CD147 plays a central role in tumor cell invasion and metastasis (15, 22, 23); second, the endocytic recycling determines the cell surface level of CD147, which in turn enhances malignant phenotypes of cancers (27, 28, 29); third, CD147 enters cells via CIE and recycled through tubular recycling endosomes specified for CIE cargoes (30, 31).