FIG. 1.

Mutation of the Rb1 pathway leads to constitutive Akt-473. (A) Western blot showing the levels of Akt-473 in the indicated proliferating cells. (B) Western blot showing the levels of Akt-308 in proliferating cells. (C) Western blot showing that the level of Akt-473 becomes elevated and independent of serum with mutation of the Rb1 pathway and that Ras activation does not further affect the level of Akt-473 when the Rb1 pathway is mutated. (D) TKO MEFs were infected with a retrovirus expressing V12 Ras to create TKO RAS cells, and activated Ras was assessed by Western blotting after binding to Gst-Raf as described in Materials and Methods. Lanes not used in the original blot were spliced out.