Endogenous levels of stevor expression affect erythrocyte deformability. (A) Retention rates in microsphere matrices at 34 hpi for erythrocytes infected with the NF54 clonal lines B3, H4, B3B1, E10, and A12. Gray represents clones exhibiting significant expression of a least one stevor gene; and red, stevor nonexpressing clones. Measurements were performed on 2% hematocrit cultures containing 2% to 10% tightly synchronized parasites. (B) Average retention rate in microsphere matrices at 34 hpi for erythrocytes infected with clones that do not express stevor genes (red) is significantly different from that of clones expressing at least one stevor gene (gray), as measured by a Wilcoxon rank-sum test. (C) Kinetics of retention in microsphere matrices for B3 (gray) and B3B1 (red) parasite lines during parasite life cycle. Measurements were performed at 10, 16, 22, 28, 34, and 40 hpi on 2% hematocrit cultures containing 2% to 10% tightly synchronized parasites.