AICAR (5-aminoimidazole-4-carboxamide ribonucleotide) is a potent and widely used AMPK activator, employed in metabolic, cellular energy, and signal transduction studies. It is cell-permeable and acts to elevate intracellular ZMP (an AMP analogue), thereby activating AMPK and downstream catabolic pathways such as fatty acid oxidation and glucose uptake. In research settings, AICAR is used to explore mechanisms of energy homeostasis, mitochondrial function, insulin sensitivity, and cell stress responses. Though primarily known for its AMPK-dependent effects, some studies report AMPK-independent actions in certain contexts, so careful experimental controls are recommended