The discussion focuses on the metabolic changes that occur with aging, its consequences for GGA availability, and the compensatory role of cytochrome P450 3A4 (CYP3A4), a hepatic enzyme that may partially substitute for MAOB in GGA synthesis (Tabata and Shidoji, 2022) but also potentially promotes tumor progression (Mohamed et al., 2024). Here, MAOB is linked to neoplasm.