Autoradiographs of Rap2A after exposure to radioactive prenyl anchor precursors. Fluorography of GST-Rap2A-fusion protein on a Western membrane after treatment with En3Hance-spray (2-methyl-naphtalene, Perkin-Elmer), showing a protein size marker in lane 1, wildtype GST-Rap2A translated with [3H]mevalonic acid in lane 2, GST-Rap2A C180A with [3H]mevalonic acid in lane 3, GST-Rap2A with [3H]FPP in lane 4 and GST-Rap2A with [3H]GGPP in lane 5. A) film after exposure for 7 days, B) film after exposure for 20 days at -80°C. There is no sign of incorporation of GGPP as detected with the TLC-scanner, underscoring the higher sensitivity of our new method. It should be noted that it is difficult to evenly spread the En3Hance-substance over all membrane area. Therefore, it is not surprising that the relative signal intensities are not identical between TLC scanning and autoradiography.