phate is an inhibitor of fructose 1,6-bisphosphatase , an enzyme of gluconeogenesis (see p. 120 for a discussion of the regulation of gluconeogenesis). The reciprocal actions of fructose 2,6-bisphos- phate on glycolysis (activation) and gluconeogenesis (inhibition) ensure that both pathways are not fully active at the same time, preventing a futile cycle in which glucose would be converted to pyruvate followed by resynthesis of glucose from pyruvate.]