Figure 10. Assessment of TEM8 functionality as an anthrax toxin receptor. A,

Sensitivity of cells expressing V1, V2, or V4. The plasmid-encoded receptors were expressed in the receptor-negative host PR230 as described in Materials and Methods, followed by cytotoxicity assays with PA+FP59. B, Toxin concentrations required for 50% cell death (IC₅₀, ng/mL) for PR230 expressing V1, V2, or V4. The means of 2–3 independent experiments are shown in parentheses. The greater sensitivity of the parental cells, WTB111, is probably due to expression of both receptors, especially CMG2/ANTXR2, which has about 10 times greater affinity for anthrax toxin protective antigen than does TEM8 [40], [4], [33].