CBI1 is a covalent BAX inhibitor. CBI1 selectively derivatizes BAX at C126 and inhibits BAX activation by triggering ligands or point mutagenesis. CBI1 blocks t-2-hex lipidation and oligomerization of BAX. CBI1 inhibits BAX activation induced by BH3 ligands, F116A mutagenesis or t-2-hex.