Regulation of TF in platelets. TF on the surface of activated platelets may be derived from (i) binding of TF-positive MPs, (ii) TF stored in α-granules, and (iii) splicing of TF pre-mRNA and translation of the mature mRNA into protein. Once at the cell surface, TF may require activation to reveal its procoagulant activity (*). The dashed lines with question marks identify possible sources of α-granular TF in platelets that require further investigation.