Phosphofructokinase-1 (PFK-1) is a crucial enzyme in glycolysis and acts as a key regulator of glucose breakdown for energy. PFK-1 is strongly controlled by several factors, including substrate and product levels, as well as allosteric regulators such as ATP, ADP, and citrate. However, one molecule that influences PFK-1 regulation in glycolysis is missing from this list. Which one?