BFAR (bifunctional apoptosis regulator) is a membrane-bound E3 ubiquitin ligase that functions as a multifaceted immunoregulatory protein with complex roles in both promoting and suppressing apoptosis depending on cellular context. Mechanistically, BFAR mediates K63-linked ubiquitination of TGFBR1 to activate TGFβ signaling crucial for Th9 cell differentiation 1, while also promoting K48-linked ubiquitination and proteasomal degradation of various substrates including PNPLA3 in lipid metabolism 2 and PRP19 in gastric cancer 3. BFAR suppresses cytokine-induced JAK2 signaling by activating JAK2 deubiquitination, thereby limiting STAT1-mediated CD8+ T cell reprogramming 4. In disease contexts, BFAR elevation promotes gastric and glioma cancer progression: it activates PI3K/AKT/mTOR signaling in gastric cancer 5, orchestrates neutrophil-mediated immunosuppression through the PRP19-YBX1 axis 3, and is inversely correlated with survival in glioma 6. Therapeutically, BFAR inhibition restores antitumor CD8+ T cell function in aged individuals and enhances checkpoint immunotherapy response, while BFAR elevation in Th9 cells promotes anti-tumor immunity 14. These findings establish BFAR as a critical immunoregulatory node with translational potential as a therapeutic target.