ABI1 (abl interactor 1) is an adapter protein that coordinates cytoskeletal reorganization with growth signaling and DNA repair. Primary function: ABI1 acts as a key link between receptor tyrosine kinase signaling and actin cytoskeleton remodeling through interaction with PI3-kinase and the WAVE complex 1. The protein functions in the GTP-Rac1-PP5-Abi-1 signaling axis, where dephosphorylated ABI1 promotes nonhomologous end joining in DNA repair 2. In pancreatic cancer, alternative splicing generates ABI1 isoforms that promote cell migration and metastasis 3. Disease relevance: ABI1 dysfunction associates with multiple malignancies. In pediatric acute myeloid leukemia, KMT2A::ABI1 fusion (10p11.2) independently predicts adverse outcomes 4. In breast cancer, ABI1 expression correlates with metastatic burden and poor survival, with genetic ABI1 disruption reducing lung metastases dose-dependently 5. In gastric carcinoma, ABI1 downregulation correlates with advanced disease, with 5-year survival rates of 15.3% (ABI1-negative) versus 63.7% (ABI1-positive) 6. In glioblastoma, ABI1-mediated DNA repair promotes resistance to genotoxic therapy 2. Clinical significance: ABI1 represents both a prognostic biomarker and therapeutic target, with splice-switching approaches and pathway inhibition showing promise for cancer treatment.