PF4 message and protein levels. (A) RT-PCR of mPF4 and mPBP (as a positive platelet control) using total platelet RNA message from mPF4^+/+, mPF4^+/–, and mPF4^–/– animals. (B) Immunoblot using a mPF4-specific primary antibody of equal amounts platelet total proteins from mPF4^+/+, mPF4^+/–, and mPF4^–/– animals (top). A Coomassie blue stain done on a parallel gel confirms equal protein loading (bottom). The arrow points to the mPF4 band. (C) Same as in panel B but for hPF4 using a hPF4-specific primary antibody. WT = wild-type mouse. Human refers to human platelet protein control.