CRC data are often summarized by the concentration required to induce a response halfway between the minimum and maximum. For inhibition assays, the IC 50 specifies the half-maximal inhibitory concentration. For a agonist/stimulator assay, the EC 50 is the concentration of substance that elicits half of the maximal response. IC 50 /EC 50 values are often used to classify the potency of a compound against a target. For example, drugs may be categorized as high potency (below 1 µM), medium potency (between 1 and 10 µM), or low potency (above 10 µM). ?