PIPOX (pipecolic acid and sarcosine oxidase) is a flavoenzyme that catalyzes the oxidation of L-pipecolate to Δ1-piperideine-6-carboxylate (P6C) as part of the lysine catabolic pathway, with subcellular localization in mitochondria 1. The enzyme plays a critical role in cellular stress protection, as PIPOX knockdown abolishes pipecolate-mediated protection against hydrogen peroxide-induced cell death 1. The protective mechanism involves activation of mTORC1/mTORC2 and Akt signaling pathways, leading to phosphorylation of FoxO3 transcription factor 1. In cancer contexts, PIPOX expression varies significantly across breast cancer subtypes, with highest expression in HER-2 type tumors and lowest in triple-negative breast cancer 2. PIPOX expression is associated with clinical outcomes, as positivity correlates with shorter overall survival in metastatic breast cancer, particularly in lung metastases 3. The enzyme shows higher expression in invasive lobular carcinoma compared to invasive ductal carcinoma and correlates with androgen receptor positivity 4. Additionally, PIPOX has been identified as a fusion partner (TAOK1::PIPOX) in high-grade serous ovarian carcinoma, suggesting potential roles in tumorigenesis 5.