PMAIP1 (also known as NOXA) is a pro-apoptotic BH3-only protein that functions as a critical mediator of cell death across multiple contexts. Mechanistically, PMAIP1 promotes activation of caspases and apoptosis by inducing mitochondrial membrane permeabilization and cytochrome c release 1. It operates through direct protein-protein interactions, competing with BAK1 and BIM for binding to the anti-apoptotic protein MCL1, thereby displacing these factors and promoting MCL1-mediated apoptosis 1. PMAIP1 plays a central role in p53-dependent apoptosis following DNA damage 2 and is also activated through endoplasmic reticulum stress pathways 3. Clinically, PMAIP1 is highly relevant to acute myeloid leukemia (AML) treatment. It is essential for synergistic activity between the BCL2 inhibitor venetoclax and 5-azacitidine, with PMAIP1 induction occurring within hours of 5-azacitidine treatment via the integrated stress response 1. CRISPR/Cas9 validation confirmed PMAIP1 as a key determinant of venetoclax sensitivity, with PMAIP1 loss conferring resistance 2. Beyond hematologic malignancies, PMAIP1 shows therapeutic potential in solid tumors and degenerative diseases. In lung cancer, parthenolide-induced apoptosis depends on PMAIP1 upregulation 3, while engineered CAR T cells expressing granzyme B-NOXA fusion proteins demonstrate enhanced myeloma killing 4. Additionally, PMAIP1 modulation shows promise in Alzheimer's disease, where siRNA-mediated knockdown alleviates mitochondrial dysfunction 5.