Comparison of in vitro intracellular amastigote (A and C) and extracellular promastigote (B and D) susceptibility to the selected AP series between the wild-type parent (LEM3323Cl4) and the successfully cultured adapted clones of the DNDI-1044-selected (A and B) and DNDI-8012-selected (C and D) resistant lines. Results are expressed as the mean IC50 ± SEM and are based on two independent replicates run in duplicate (*, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001). For DNDI-8012-generated clones, only a few clones were selected for amastigote susceptibility assessment.