SHKBP1 is a regulatory protein that functions as a positive modulator of epidermal growth factor receptor (EGFR) signaling. Primary Function: SHKBP1 inhibits CBL-mediated EGFR degradation by sequestering SH3KBP1 and preventing its interaction with c-Cbl, thereby blocking the c-Cbl-CIN85 complex formation 1. This interruption prevents translocation of regulatory proteins to EGFR-containing vesicles and reduces EGFR internalization, thus enhancing EGF-induced signaling activity. Mechanism: SHKBP1 contains two PXXXPR motifs that allow it to competitively bind to the SH3 domains of CIN85, preventing CIN85 from engaging with c-Cbl 1. Recent evidence indicates SHKBP1 also functions as a cullin-3 E3 ubiquitin ligase adaptor regulating p62 oligomerization and the antioxidant response independent of ubiquitination 2. Disease Relevance: SHKBP1 is identified as a significantly mutated gene in cervical cancer 3 and serves as a survival-associated biomarker in serous ovarian cancer 4. Elevated SHKBP1 expression promotes tumor migration and invasion through epithelial-mesenchymal transition, with SHKBP1 knockout suppressing tumor growth and metastasis 5. In osteosarcoma, the TGFβ-miR-499a-SHKBP1 pathway mediates resistance to EGFR inhibitors 6. Clinical Significance: SHKBP1 is emerging as a diagnostic and prognostic biomarker in sepsis 7, and genetic variations in SHKBP1 associate with immune cell-mediated responses to tyrosine kinase inhibitor therapy in chr19 myeloid leukemia 8.