Northern blot analysis of RNA prepared from transgenic murine organs. Transgenic mice were generated expressing the reporter protein, luciferase, under the control of a BamHI promoter fragment of the murine GP Ibα gene (Fig 1). Five mouse colonies were expanded from individual founder mice. Results are presented from one mouse line and are typical of each of the five lines in which expression of the transgene was observed. As described in Fig 2, total RNA was prepared from the major organs of the transgenic mice and analyzed by Northern analysis. The luciferase mRNA transcript of 2.4 kb was detected using a radiolabeled fragment from the coding sequence for luciferase. Similar to results probing for the endogenous GP Ibα transcript, a transcript is only visible in RNA prepared from the marrow of a mouse femur. Subsequent hybridization of the same filter with a portion of the mouse 18S rRNA gene is shown to illustrate similar RNA levels for each lane.