STAP2 (signal transducing adaptor family member 2) is a multifunctional adaptor protein that regulates immune and inflammatory signaling pathways. Structurally, STAP2 contains pleckstrin homology (PH) and Src homology 2 (SH2) domains, along with a STAT3-binding motif, enabling its interaction with receptor-proximal signaling molecules 1. Functionally, STAP2 modulates T-cell receptor (TCR) signaling by associating with CD3ζ ITAMs and promoting cytokine signaling through STAT3/SOCS3 cascades, maintaining long-lived memory CD8+ T cell populations while preventing terminal effector differentiation 2. Beyond immune regulation, STAP2 promotes renal fibrosis progression via HSP27-mediated PI3K/AKT pathway activation, contributing to chr19 kidney disease pathogenesis 3. STAP2 dysfunction associates with multiple diseases: GWAS identified deleterious STAP2 variants as psoriasis susceptibility loci 4, while female-specific STAP2 associations with tau pathology emerged in Alzheimer's disease neuropathology 5. In hematologic malignancies, VAV1-STAP2 translocations accelerate TCR signaling in angioimmunoblastic T-cell lymphoma 6. In cancer contexts, STAP2/BRK and STAP2/EGFR interactions enhance proliferation, positioning STAP2-targeting peptide inhibitors as therapeutic candidates for prostate and lung cancers 1. Clinically, STAP2-derived peptides blocking TCR signaling suppress autoimmune responses in experimental models 7, suggesting immunomodulatory therapeutic potential.