PTPN13 encodes a non-receptor protein tyrosine phosphatase with dual roles in cancer, functioning both as an oncogene and tumor suppressor depending on cellular context 1. The protein negatively regulates FAS-induced apoptosis and NGFR-mediated pro-apoptotic signaling, while potentially modulating PI3K signaling through PIK3R2 dephosphorylation. PTPN13 participates in multiple signaling complexes, including regulation of ErbB2, Src, and EphrinB1 interactions that influence MAP kinase signaling in breast cancer 2. In colorectal cancer, PTPN13 loss leads to immune evasion through STAT1 dephosphorylation, independently of β-catenin signaling, inhibiting CD8+ T cell infiltration and MHC class I antigen presentation 3. Clinically, PTPN13 genetic polymorphisms show disease-specific associations: rs989902 variants increase risk for esophageal squamous cell carcinoma 4, head and neck squamous cell carcinoma 5, and colorectal cancer in Polish populations 6. In breast cancer, PTPN13 mutations correlate with shorter disease-free survival 7, while high expression associates with favorable prognosis. These findings highlight PTPN13's complex role in cancer biology and its potential as both a prognostic biomarker and therapeutic target.