In vitro susceptibility of P. berghei to different anti-malarial drugs. Inhibition of schizont maturation by amodiaquine (squares), chloroquine (solid circles), artesunate (solid triangles) and quinine (asterisks). Curves derived from micro-test assays are displayed as dashed lines and open symbols. Each point represents the mean and the standard error of at least three independent assays for PbA and PbAGFP. The IC50 values and standard error of the media are shown in the legend.