PTPN6 (also known as SHP-1) is a non-receptor protein tyrosine phosphatase that serves as a critical negative regulator of immune signaling and hematopoiesis 12. Mechanistically, PTPN6 dephosphorylates receptor tyrosine kinases (EGFR, PDGFR, FGFR) and is recruited to ITIM-containing inhibitory immune receptors including CD33, PDCD1, and CD22, where it suppresses downstream signaling 345. PTPN6 also targets cytoplasmic signaling molecules including STING1, LCK, and STAT1, modulating T-cell activation and innate immune responses 67. In inflammation, PTPN6 dysfunction promotes increased inflammatory cytokines and systemic inflammation, with impaired PTPN6 associated with neutrophilic dermatosis 8. Clinically, PTPN6 dysregulation has implications across multiple disease contexts: in acute myeloid leukemia, PTPN6 inhibition reduces cell viability and synergizes with chemotherapy 9; in colorectal cancer and other malignancies, PTPN6 expression correlates with tumor immunity and prognosis, particularly in glioblastoma and melanoma 10; and CD33-PTPN6 interactions modulate Alzheimer's disease risk 4. These findings establish PTPN6 as a multifunctional immune regulator with therapeutic potential as both a target in hematologic malignancies and a biomarker in various cancers.