TIAM2 (T-cell lymphoma invasion and metastasis 2) is a Rac1-specific guanine nucleotide exchange factor (GEF) that promotes malignant transformation and metastasis across multiple cancer types 1. The protein functions as a GDP-dissociation stimulator, catalyzing GDP-GTP exchange on RAC1 to activate downstream cytoskeletal reorganization pathways 1. TIAM2 expression is significantly upregulated in various cancers including hepatocellular carcinoma (86% of cases), lung adenocarcinoma, osteosarcoma, and esophageal carcinoma, where it correlates with poor prognosis and metastatic potential 234. Mechanistically, TIAM2 promotes cancer cell migration and invasion through multiple pathways: it activates JAK2/STAT3 signaling in osteosarcoma 3, facilitates epithelial-to-mesenchymal transition by upregulating N-cadherin and vimentin while redistributing E-cadherin 2, and operates downstream of receptor tyrosine kinases like EGFR and c-Met in lung cancer 5. Additionally, TIAM2 in cancer-associated fibroblasts promotes tumor cell invasion through secretion of factors like osteoprotegerin 6. The protein also contributes to drug resistance, particularly osimertinib resistance in lung adenocarcinoma, partly through promoting M2-like tumor-associated macrophage polarization 7.