RAP1A and neoplasm: In subcutaneous models, tumor tissues in ZOL or VPA + ZOL treated BALB/c-nu mice showed marked unprenylated Rap1A and Ras expression, which were demonstrated in immunofluorescence and western blotting (Figures 5A–C), while these unprenylated proteins were hardly detected in VPA-treated or untreated xenografts.