Mobility changes of the prenylated protein form: Immunoblot analysis of Rap2A. Western blot analysis has been performed on lysates of exponentially growing cells. U denotes the unmodified, P the prenylated form of Rap2A. A) HeLa cells have been transiently transfected with HA-Rap2A (lanes 1–4). Upon treatment with lovastatin (lane 2), the signal representing prenylated (p) Rap2A disappeared. This effect could be reversed by adding FPP (lanes 3 and 4), but not by adding GGPP (data not shown). B) HeLa cells have been transiently transfected with HA-Rap2A (lanes 2 and 3) or HA-Rap2A with a cysteine-to-alanine mutation within the C-terminal CAAX prenylation motif (lane 1, mutation C180A). The mutation and also the lovastatin treatment prevent the prenylation of HA-Rap2A.