PRELID3B (also known as SLMO2) is a mitochondrial lipid transfer protein belonging to the conserved Ups/PRELI family that mediates phospholipid transport across the mitochondrial intermembrane space 1. Structurally, PRELID3B forms a complex with TRIAP1 and exhibits specific transfer activity for phosphatidylserine, with lipid specificity determined by amino acids involved in head group recognition and flexible loop hydrophobicity 1. At the functional level, PRELID3B regulates intramitochondrial phosphatidylserine transport to facilitate phosphatidylethanolamine synthesis, which subsequently modulates Snf1/AMPK signaling and mitochondrial energy metabolism 2. Clinically, PRELID3B shows significant disease relevance in cancer biology: knockdown of PRELID3B decreased viability in Rb1-deficient breast cancer cells 2, and pan-cancer analysis reveals that PRELID3B is overexpressed across multiple tumor types and correlates with poor prognosis 3. In vitro experiments demonstrate that PRELID3B promotes proliferation and migration of breast and lung cancer cells, with expression positively correlating with myeloid-derived suppressor cell infiltration 3. These findings suggest PRELID3B represents a potential prognostic biomarker and therapeutic target for cancer treatment.