What dose of an antagonist, agonist, or signaling tool should be used in vitro?

   The amount of antagonists, agonists or ssignaling tool required depends on many factors, including targeted accessibility, duration of incubation, and type of cells or assay used. It is best to survey the literature to determine the IC50 value (the concentration of inhibitors when reaching 50% inhibitory effect) EC50 value (the concentration when the drug reaches 50% of the maximum clinical efficacy (which can be inhibition or stimulation)) or Ki value (the concentration of the inhibitor when 50% inhibition effect is measured (obtained by Michaelis equation dynamics calculation)). For an inhibitor, if published Ki or, IC50 values are known, we recommend that you use 5 to 10 times higher than these values to maximally inhibit enzyme or receptor activity. If there are no published values we recommend that you perform dose-response experiments (running appropriate controls) and use Michaelis-Menten kinetics to determine the Ki value.