has mode of action has percent response based on normalization percent inhibition normalization growth inhibition TGI TGI is total growth inhibition, which is the effective concentration of a growth inhibitor, which produces 0% relative growth for that inhibitor. Thus TGI signifies a cytostatic effect. tgi is calculated from [(Ti-Tz)/(C-Tz)] x 100 =0, where Ti = Tz and Tz is absorbance at time zero, Ti is absorbance in the presence of test drug, and C is absorbance in the control (untreated cells). As a measure of viable cells, different researchers measure different parameters, namely, protein content (by sulforhodamine B staining followed by absorbance measurement), mitochondrial dehydrogenase activity (by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide, known as MTT staining followed by absorbance measurement), and ATP content (by using CellTiter-Glo reagent (Promega) followed by luminescence measurement). total growth inhibition 100 percent growth inhibition concentration response endpoint