PTP4A2 is part of a small class of the protein tyrosine phosphatase（PTP) family. PTP4A2 is localized to the early endosome that take part in a variety of cellular activities. PTP4A2 protein interacts with the beta-subunit of Rab geranylgeranyltransferase II（beta GGT II)， therefore has a role as a regulator of GGT II activity. Overexpression of PTP4A2 in mammalian cells conferred a transformed phenotype， which suggested its role in tumorigenesis.
