FIG. 7.

Suppression of Myr-βCC1 Fes transforming activity by coexpression with Fes N-terminal domain proteins. Rat-2 fibroblasts were infected with recombinant retroviruses carrying the wild-type Fes N-terminal sequence (N-term), the N-terminal sequence lacking the first coiled-coil homology domain (ΔCC1 N-term), or the N-terminal sequence lacking the second coiled-coil homology domain (ΔCC2 N-term). A parallel series of N-terminal constructs bearing the v-Src myristylation sequence was also tested (indicated as + Myr). Cells infected with a retrovirus carrying only the neo selection marker served as a negative control (Con). Forty-eight hours later, the cells were reinfected with a Myr-βCC1 Fes retrovirus and selected with G418 for 2 weeks as described in Materials and Methods. Foci were visualized by Wright-Giemsa staining and counted by using a Bio-Rad Model GS-710 Scanning Densitometer and colony-counting software. Foci from three independent cultures were counted and normalized to the negative control average value; the bar graph shows the average normalized value ± the SD. Expression of Myr-βCC1 and the N-terminal proteins was verified by immunoblotting with the anti-FLAG antibody, which recognizes the FLAG epitope fused to the C terminus of each protein (lower two panels). This entire experiment was performed twice and produced the same pattern of inhibition each time.