OTUB1 (OTU deubiquitinase, ubiquitin aldehyde binding 1) is a deubiquitinating enzyme that plays critical roles in cellular protection, immune regulation, and cancer progression. The protein functions primarily through both catalytic and non-catalytic mechanisms to regulate protein stability and cellular responses. OTUB1 stabilizes key proteins involved in ferroptosis resistance, particularly SLC7A11, the essential component of the cystine-glutamate antiporter 1. Through direct interaction and deubiquitination, OTUB1 prevents SLC7A11 degradation, thereby protecting cancer cells from ferroptosis-induced cell death 1. In immune regulation, OTUB1 promotes cancer immune evasion by stabilizing PD-L1 through removal of K48-linked ubiquitin chains, preventing its degradation via the ER-associated degradation pathway 2. This mechanism reduces tumor cell sensitivity to immune-mediated cytotoxicity and decreases CD8+ T cell infiltration 2. OTUB1 also regulates the stability of other proteins including NCOA4, where it maintains protein levels through deubiquitination, affecting ferritinophagy-dependent ferroptosis in myocardial ischemia-reperfusion injury 3. The enzyme's expression correlates with disease severity in various conditions, including lupus nephritis where reduced OTUB1 levels are associated with podocyte injury 4. These diverse functions establish OTUB1 as a potential therapeutic target for cancer immunotherapy and ferroptosis-related diseases.