STEVOR proteins are involved in P falciparum–infected erythrocyte rigidity. (A) Kinetics of retention in microsphere matrices for B3 (gray), SFM⁺ (green), SB3 (red), and CBM-BSD (blue) parasite cultures during the 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. (B) Retention rate in microsphere matrices at 16 hpi of the entire SFM⁺ parasite-infected erythrocyte population compared with that of the c-myc–positive SFM⁺ parasites. The proportion of c-myc–positive parasites before and after microsphere filtration was determined by immunofluorescence using anti–c-myc mAb and Hoechst 33342 for nuclei staining.