PHLDA3 is a p53-regulated tumor suppressor that functions primarily as a negative regulator of AKT/PI3K signaling 1. It contains a pleckstrin homology domain that enables direct binding to phosphatidylinositol lipids, particularly PIP3, thereby preventing AKT membrane translocation and activation 2. This mechanism allows PHLDA3 to suppress AKT-dependent proliferation and promote p53-mediated apoptosis in response to cellular stress 1. PHLDA3 is frequently inactivated in neuroendocrine tumors through loss of heterozygosity and DNA methylation, with LOH correlating with poor prognosis 1. Its tumor-suppressive role extends to squamous cell carcinomas, where PHLDA3 loss promotes epithelial-mesenchymal transition and metastasis 3. Additionally, PHLDA3 regulates reciprocal metabolic-signaling crosstalk by blocking pentose phosphate pathway-mediated AKT reinforcement 4. Contextually, PHLDA3 also promotes beta cell survival under metabolic and oxidative stress through regulation of inflammatory and antioxidant gene expression 5. However, in lung adenocarcinoma, PHLDA3 paradoxically promotes proliferation and invasion via Wnt pathway activation 6, suggesting tissue-context-dependent functional divergence. Restoration of PHLDA3 expression has emerged as a therapeutic strategy for PI3K/AKT-driven malignancies 7.