VWF level does not correlate with the degree of Stx-induced thrombocytopenia. Plasma VWF levels were obtained for the Vwf^+/+ and Vwf^+/− mice shown in Figure 1, and were plotted against the percentage platelet decrease from baseline for each mouse. The R value was calculated using Microsoft Excel (Microsoft, Redmond, WA). Diamonds indicate Vwf^+/+ mice; squares, Vwf^+/− mice.