One of the following is considered to be the key regulatory enzyme of glycolysis

Phosphofructokinase is both inducible and subject to allosteric regulation and has a major role in regulating the rate of glycolysis.These reactions, catalyzed by hexokinase (and glucokinase), phosphofructokinase, and pyruvate kinase, are the major sites of regulation of glycolysis.Phosphofructokinase is considered key regulator.Harper 30th edition pg: 172