Characterization of the platelets of Pf4-Cre/ERp57^fl/flmice. (A) The monoclonal anti-ERp57 antibody (Mab1) reacts with mouse ERp57 by western blot (with PLCγ2 loading control; 30 μg of protein). (B) Platelet reverse-transcription polymerase chain reaction products of ERp57^fl/fl and Pf4-Cre/ERp57^fl/fl mice. The primers for ERp57 gave the predicted 186-bp product in wild-type but not ERp57-deficient platelets. The primers for Cre-recombinase gave the predicted 450-bp product in Cre-positive ERp57-deficient platelets but not wild-type platelets. The primers for mouse β-actin yielded the predicted 265-bp product. (C) Western blot of lysates using the anti-ERp57 antibody (PLCγ2 control). Blotting results for PDI, ERp72, and ERp5 are shown. In panels B-C, the lanes for a specific RNA or protein were run on the same gel but were noncontiguous. (D) Platelet counts in ERp57^fl/fl and Pf4-Cre/ERp57^fl/fl mice ± SE (n = 10). (E) Normal glycoprotein expression in platelets from Pf4-Cre/ERp57^fl/fl mice compared with ERp57^fl/fl littermate controls ± SE (n = 8). Mouse platelets were incubated with antibodies to αIIbβ3, GPIb, or GPVI and analyzed by flow cytometry.