The formation and propagation of malignant cells is often associated with changes in intracellular signalling pathways. Changes in the activity and/or regulation of protein tyrosine phosphatases, for example, are known to contribute to cancer development. Overexpression of phosphatase of regenerating liver 3 (PRL3) enhances motility and invasiveness. But what are the mechanisms by which PRL3 contributes to tumorigenesis and metastasis? On page 3883, Götz von Wichert and colleagues now shed light on the cellular function of PRL3. They find that PRL3 associates with the small GTPase ADP-ribosylation factor 1 (Arf1) and that the two proteins colocalise on membranes of the Golgi complex and early and late endosomes in the perinuclear region. The interaction between PRL3 and Arf1 depends on Arf1 being activated through GTP binding, and the expression of PRL3 increases Arf1 activity. Furthermore, the authors demonstrate that PRL3 expression enhances HeLa cell migration, and that this depends on the presence of Arf1 and Arf3. In addition, PRL3 accelerates the internalization and recycling of α5 integrins, without affecting the total amount of the adhesion receptors at the cell surface. The authors propose that PRL3 facilitates tumour cell metastasis by enhancing Arf1-mediated integrin recycling and thereby altering cell adhesion and migration.
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