In the case of PRL3, Min et al found evidence that the intracellular PRL3 oncoprotein is externalized on the cell surface in tumor cells in vivo and serum-starved cells in vitro; this phenomenon is not observed in normal cultured cells in vitro, suggesting that stresses in the tumor microenvironment promote externalization of PRL3, and this can be recapitulated in vitro by subjecting cells to serum starvation 8. This evidence concerns the gene PTP4A3 and neoplasm.