Functional analysis of falcipain promoter constructs. The plasmids are shown in the left. Numbers indicate the size of 5' sequence of respective falcipain used in each plasmid. (A) Ring stage parasites were transfected with 75 μg of plasmids containing the 0.5 and 1 kb constructs of the falcipains. Co-transfection with 75 μg of renilla served as internal control for the transfection assays. Vector pGL2 (Promega) served as negative control. The luciferase gene is indicated as box. Percentage relative luciferase activity was calculated by normalizing the luciferase firefly to the renilla internal control values. The values shown represent the mean ± standard deviation of two independent transfection experiments performed in triplicates. (B) Ring stage parasites were transfected with 75 μg of plasmids containing 2 kb constructs of the falcipains.