PTP4A3 is a protein tyrosine phosphatase that functions as an oncogenic driver across multiple cancer types. Primary function: PTP4A3 stimulates cell proliferation and promotes cancer progression by dephosphorylating key regulatory proteins. Mechanism: The phosphatase operates primarily through the PI3K/AKT/mTORC1 signaling axis 1, and is transcriptionally regulated by HIF-1alpha under hypoxic conditions 2. It enhances endothelial cell migration and angiogenesis through ERK1/2, AKT, and SRC phosphorylation 3. Disease relevance: PTP4A3 overexpression correlates with poor prognosis in hepatocellular carcinoma 4, papillary renal cell carcinoma 5, high-grade serous ovarian cancer 6, and pleural mesothelioma 7. In ovarian cancer, PTP4A3 promotes chemotherapy resistance through autophagy activation 1. Clinical significance: JMS-053, a potent allosteric PTP4A3 inhibitor, blocks cell migration and synergizes with paclitaxel in ovarian cancer models 6, while pan-PTP4A inhibition overcomes compensatory mechanisms from related phosphatases 1. PTP4A3 represents a validated but underexplored molecular target for cancer therapy 8.