In vivo fibrinogen uptake and endogenous fibrinogen levels are increased in Dicer1-deficient platelets. (A) Dicer1^Pf4Δ/Pf4Δ or Dicer1^fl/fl mice were IV injected with Alexa Fluor 488 labeled fibrinogen. After 48 hours, platelets were isolated, stained with an anti-CD41 antibody, and incorporation of the label was analyzed by flow cytometry. The histogram is representative of 6 independent samples isolated from Dicer1^Pf4Δ/Pf4Δ and Dicer1^fl/fl mice (difference in gMFI P < .05; unpaired Student t test; n = 6 samples per group). (B) Bar graph representing the amount of endogenous (not injected) fibrinogen in platelet lysates obtained from Dicer1^Pf4Δ/Pf4Δ vs Dicer1^fl/fl mice, as measured by ELISA (*P < .05; unpaired Student t test; n = 7 mice per group).