PXMP2 (peroxisomal membrane protein 2) is the most abundant peroxisomal membrane protein in higher eukaryotes, with tissue-specific expression highest in liver, kidney, and heart 1. It functions as a non-selective pore-forming protein that facilitates metabolite transport across the peroxisomal membrane, with a molecular size selectivity limit of 300-600 Da 2. PXMP2 enables transfer of water-soluble metabolites including β-oxidation products and cofactors like ATP across peroxisomal membranes 2. Functionally, PXMP2 also regulates intracellular NMN metabolism and the NMN/NAD+ ratio 3. Beyond its canonical metabolic role, PXMP2 demonstrates tumor-suppressive properties in hepatocellular carcinoma by inhibiting cancer stem cell characteristics and promoting anti-tumor M1 macrophage infiltration while suppressing immunosuppressive M2 macrophages 4. High PXMP2 expression correlates with favorable prognosis in HCC patients 4. PXMP2 also serves as a metabolism-related biomarker in osteosarcoma prognostication 5. Notably, PXMP2 is not essential for hydrogen peroxide permeation across the peroxisomal membrane 6, and functions in peroxisome fission and segregation 7.