PF4 and neoplasm: At the earliest time point of seven days post-implantation, ectopic KPC tumors implanted in Dicer1fl/fl/Pf4-Cre mice displayed a mean volume of 130.1 ± 16.7 mm3, compared with 58.9 ± 10.0 mm3 in control mice, a 2.2-fold increase in tumor volume in mice with platelet-specific loss of miRNAs at this initial time point (Fig 1A).