The high molecular weight of the proteins detected by Western blotting (Fig. 2F ) suggested that the monoclonal antibodies were specific for members of the so far bestcharacterized family of VSA, PfEMP1 (Leech et al., 1984) . This family includes VAR2CSA (predicted molecular weight: 355 kDa), which is the only PfEMP1 described so far that has the characteristics expected of VSAPAM (Salanti et al., 2003; 2004) . We therefore used a panel of recombinant proteins spanning the entire extracellular b. 3D7 (Walliker et al., 1987) was originally cloned from, and appears genetically identical to, NF54 ( Delemarre and Van der Kaay, 1979) . c. Line used in screening of B-cell supernatants for production of VSAPAM-specific IgG. n.d., not determined.