WBP2 (WW domain binding protein 2) is a multifunctional transcriptional coactivator and adaptor protein with roles spanning hormone signaling, cell survival, and disease pathogenesis. Primary Function: WBP2 acts as a transcriptional coactivator of estrogen receptor (ESR1) and progesterone receptor (PGR), binding to hormone-responsive promoters upon estrogen activation and synergizing with YAP1 to enhance PGR activity 1. Beyond nuclear hormone signaling, WBP2 functions as a molecular chaperone in cytoprotective pathways. Mechanism: WBP2 interacts with multiple WW domain-containing proteins (YAP, TAZ, WWOX) through its PPxY motifs 2, positioning it as a central hub connecting diverse signaling pathways including EGFR, PI3K, Hippo, and Wnt 3. At the protein level, WBP2 restrains lysosomal degradation of GPX4 (glutathione peroxidase 4) by competing with HSC70 for GPX4 binding, thereby inhibiting ferroptosis 4. Disease Relevance: WBP2 is an emerging oncogene implicated in breast, ovarian, and prostate cancers, where dysregulation promotes malignant progression and drug resistance 56. Additionally, WBP2 promotes neointimal hyperplasia post-vascular injury by facilitating YBX1 nuclear translocation 7. Clinical Significance: WBP2 serves as a biomarker for early detection and prognosis in breast cancer and represents a promising therapeutic target, with nuclear WBP2 being particularly meaningful for diagnosis and progression prediction 6.