A ribbon representation of LAAO (PDD ID: 5Z2G, Naja atra venom) is illustrated in (a). The LAAO is a homodimeric flavoenzyme containing a substrate-binding domain (yellow colour of mixed β-pleated sheet), a flavin adenine nucleotide (FAD) binding site and a helical domain (red colour). The enzyme catalyses the oxidative deamination of l-amino acid and produces H₂O₂ as the main mediator for its cytotoxicity, as illustrated in (b). LAAO exerts apoptosis in cancer cells through extrinsic and intrinsic pathways. It is noteworthy that there is an up-regulation of CYP450 gene families to further enhance the oxidative by producing excessive ROS. On the contrary, the cell cycle arrest gene CDKN2B is down-regulated after exposure to LAAO. The CDKN2B is the main cell cycle regulator that inhibits G1 progression. It explains the role of LAAO in cell cycle arrest at the Go–G1 phase. Abbreviations: DISC-FADD, death-inducing signalling complex and Fas-associated death domain; MMP, mitochondrial membrane potential; BMP, Bcl2 modifying factor; IGFBP3, Insulin-like growth binding protein 3; PLEKHF1, Pleckstrin homology domain containing family F member 1; HSPD1, heat shock 60 kDa protein 1; SQSTM1, Sequestosome 1; MLF1, myeloid leukaemia factor 1; KLF10, Kruppel-like factor 10; CDKN2B, Cyclin-dependent kinase inhibitor 2B.