FIG. 1.

Transduction of human cells by GRP virus. NIH 3T3 cells, human A375 melanoma cells, and human MDA-MB-231 breast carcinoma cells were infected with a GRP virus, selected with G418 for 2 weeks, fixed, and stained with Giemsa, and the colonies were counted. Amphotropic (Amph) and ecotropic virus (Eco) was generated by expressing the wild-type amphotropic and ecotropic envelopes, pCAA and pCEE, respectively. Note the log scale. The amphotropic envelope, pCAA, and the LAPNL packaging vectors were generated as described elsewhere (12); the latter expresses the secreted alkaline phosphatase (SEAP) gene and the neomycin resistance gene.