RUBCNL (Rubicon-like autophagy enhancer), also known as PACER, is a critical regulator of autophagy that promotes autophagosome maturation and autolysosome formation. The protein facilitates autophagosome-lysosome fusion by interacting with autophagosomal proteins STX17 and forming complexes that recruit the HOPS complex 12. RUBCNL enhances autophagy by antagonizing RUBCN and stimulating PI3K activity, promoting phosphatidylinositol 3-phosphate biogenesis essential for late-stage autophagy 3. Beyond autophagy regulation, RUBCNL functions as a negative regulator of RIPK1-dependent apoptosis and necroptosis by forming complexes with RIPK1 and limiting TNF signaling 4. The protein's expression is regulated by histone lactylation, particularly H3K18 lactylation, which promotes RUBCNL transcription in hypoxic conditions and contributes to bevacizumab resistance in colorectal cancer 56. In neurological contexts, RUBCNL levels must be precisely balanced, as both loss and overexpression can impair autophagy and worsen disease outcomes in ALS models by affecting SOD1 aggregate clearance 7. The protein's dual roles in autophagy enhancement and cell death regulation make it a potential therapeutic target, though careful modulation is required to maintain cellular homeostasis.