A transgene was created from a BAC where cre-recombinase is driven by the Cxcl4 (Platelet factor 4) promoter. This transgene also contains the Cxcl3, Cxcl5, Ppbp, and Cxcl15 genes. This line has one copy of the transgene inserted with expression restricted to megakaryocytes and platelets, as demonstrated by RT-PCR and Western blotting.