FIG. 4.

Analysis of the Gag and Pol expression profile in cell extracts and extracellular particulate material from cells cotransfected with 5′ UTR-deleted PFV vectors shown in Fig. 3A and pol and env expression constructs. A representative example of three experiments is shown. M, relative molecular mass standards in kilodaltons. (A) Detection of Gag and Pol proteins in cellular lysates from transfected cells. (B) Immunoblot analysis of Gag proteins in viral particles sedimented through a sucrose cushion.