Bax

BAX (BCL2-associated X protein) is a pro-apoptotic member of the BCL-2 family that regulates programmed cell death through mitochondrial apoptosis and functions as a critical determinant of cellular survival following apoptotic stimuli^[1][2]. BAX forms heterodimers with anti-apoptotic BCL-2 proteins, and the balance between BAX and BCL-2 influences mitochondrial outer membrane permeabilization (MOMP), cytochrome c release, and activation of the intrinsic apoptotic pathway^[2][3][4]. Mechanistically, BAX belongs to the pore-forming executioner subgroup of the BCL-2 family and undergoes activation in response to cellular stress signals, including p53-dependent apoptotic signaling, thereby promoting mitochondrial membrane permeabilization and irreversible cell death commitment^[1][3][5]. In disease models, dysregulated BAX activity contributes to the pathophysiology of cancer, neurodegenerative disorders, and other apoptosis-associated conditions, making mitochondrial apoptosis a major target for therapeutic intervention^[3][4][6]. Compared with related BCL-2 family isoforms, BAX is distinguished by its direct executioner function in apoptosis, whereas many alternative BCL-2 family isoforms display variable anti-apoptotic or context-dependent activities that remain incompletely characterized^[3]. A notable BAX isoform, BaxΔ2, retains pro-apoptotic activity despite N-terminal alterations, highlighting functional diversity within the BAX locus and providing experimental models for studying non-canonical apoptotic mechanisms^[7]. For experimental applications, BAX-dependent signaling is widely used to evaluate mitochondrial apoptosis, while therapeutic strategies targeting BCL-2 family interactions, including BH3 mimetics, are actively investigated to modulate BAX-mediated cell death in cancer research^[3][6].