Analysis of platelet Mpl levels by Western blot. Platelet lysates (20 μg per lane) were separated by 8% SDS-PAGE and immunoblotted with an anti-human Mpl antibody and an HRP-conjugated second antibody. Detection was carried out by chemiluminescence. To control for protein loading, membranes were reprobed with an anti-β₃ integrin antibody. (A) Representative Western blot experiment shows the results of a healthy control (C) and patients (P), who reveal decreased Mpl levels. (B) Expression of Mpl relative to that of β₃ integrin. Bars represent the ratio of Mpl to β₃ integrin, which was calculated by densitometry and expressed as percentage of healthy controls (n = 6), set as 100%. Data represent the mean of 3 separate experiments.