Effect of Syk inhibitors on P falciparum intraerythrocytic growth cycle. (A) Parasitemia during the course of 2 growth cycles; R406 was added at 14 to 20 hours postinfection. (B) Number of merozoites per schizont measured at 48 hours postinfection. Data are the average of 7 experiments ± SD. (C) DNA synthetic activity measured at 42 to 48 hours postinfection using the untreated cells as a reference (% DNA synthesis). (D) The amount of hemozoin produced by the parasite during maturation from ring to late trophozoite/schizont stage in the infected RBCs in the presence of R406 and in untreated parasites. Hemozoin was quantified in terms of heme content and is expressed as mean hemozoin-heme per infected RBCs. Data are the average ± SD of 4 independent experiments. * Significant differences to untreated control parasites at P < .05.