FIG. 7.

c-myc activation is not required for transformation by mutated β-cat, but increased c-myc expression can contribute to a more aggressive phenotype. (A) A polyclonal RK3E line with stable expression of a dominant negative c-Myc mutant protein (i.e., MycΔ106–143) was generated and termed RK3E/MycΔ106–143. Activation of a c-Myc-responsive reporter (pGLDH637Luc) is substantially inhibited in the RK3E/MycΔ106–143 line. (B) Mutated β-cat proteins induce focus formation in RK3E/MycΔ106–143, but the size of the foci is reduced compared to those induced by mutated β-cat in the control RK3E/Neo line. (C) Colony formation in soft agar following infection with a K-Ras retrovirus is not inhibited in RK3E/MycΔ106–143 cells.