Drug susceptibility was measured by growth assay as previously reported.36 (link) Briefly, synchronized ring stage parasites were cultured in the presence of 12-point serial dilutions of the test compounds in triplicate in 384-well black clear-bottom plates for 72 h. SYBR Green I fluorescent dye (Invitrogen S7563) was added, and after overnight incubation at room temperature, fluorescence was read (excitation and emission wavelengths of 485 and 535 nm, respectively). EC50 values were calculated using a nonlinear regression curve fit in Prism Software version 6 (GraphPad). The assay was replicated 3–5 times.