PTPN12 (protein tyrosine phosphatase non-receptor type 12) is a cytoplasmic phosphatase that regulates cellular signaling by dephosphorylating tyrosine-phosphorylated proteins. PTPN12 specifically targets key signaling molecules including ERBB2 and PTK2B/PYK2, selectively dephosphorylating ERBB2 at tyrosine residues 1112, 1196, and 1248, thereby modulating ERBB signaling pathways 1. The protein functions as a tumor suppressor gene, with inhibition of its activity leading to uncontrolled cell growth and tumor development 2. In hepatic stellate cells, PTPN12 is regulated by sulfiredoxin-1 through desulfinylation, which enhances its phosphatase activity and protein stability, ultimately inhibiting NLRP3 inflammasome activation and reducing liver fibrosis 3. PTPN12 inactivation in triple-negative breast cancer drives mitotic defects through aberrant hyperactivation of the APC/FZR1 ubiquitin ligase complex, leading to chr7 instability and increased sensitivity to microtubule-targeting agents 4. Additionally, PTPN12 plays roles in osteoarthritis progression through the miR-940/PTPN12 pathway 5 and has been identified as a potential therapeutic target for hypertension 6. These diverse functions highlight PTPN12's importance in regulating cell cycle fidelity, tumor suppression, and inflammatory responses.