Luciferase activity in transgenic platelets. A linear correlation exists between the number of platelets and luciferase activity in the transgenic mice. PRP and PPP from transgenic mice (colony 32) was used to resuspend blood cells and subsequently determine luciferase activity. These reconstitution experiments confirmed the luciferase activity in whole blood coincides completely with the presence of platelets with a linear correlation between luciferase activity and the number of platelets (r² = 0.88).