NEU4, like NEU1, was thought to be localized in lysosomes, where it plays a role in the degradation of the sialoglycoconjugate by eliminating the terminal sialic acid.[34, 44] Besides lysosomes, recent findings have indicated the localization of NEU4 within mitochondria, endoplasmic reticulum, and the nucleus.[24, 25, 45] In this work, we have demonstrated that NEU4 was activated in cytoplasm and translocated into the nucleus in renal fibrosis. This evidence concerns the gene NEU1 and renal fibrosis.