Figure 1.

A. Expression of RAS was verified by immunoblot analysis in MEFs transduced with pBabe (control) or pBabe-ras^V12/E1A (transformed) retroviruses. B. Morphological aspect of the pBabe and pBabe-ras^V12/E1A transduced mouse embryonic fibroblats. C. Anchorage-independent growth of the ras^V12/E1A transformed MEF. Fifty thousand cells were plated on 0.6% agar in DMEM-10% FCS and overlaid on 0.6% agar in the same medium. Photomicrographs were taken 10 days after plating. D. ras^V12/E1A transformed MEF induce tumor formation. One million of pBabe and pBabe-ras^V12/E1A transduced mouse embryonic fibroblast were injected in 200 μl PBS as xenografts in nude mice. Representative mice at day 18.