IFNα and IFNβ induce phosphorylation of the S6 ribosomal protein, in a PI 3′kinase- and mTOR-dependent manner. (A) KT-1 cells were treated with IFNα for different times, as indicated. Top panel shows an immunoblot with an antibody against the phosphorylated form of the S6 ribosomal protein on serines 235/236. Middle panel shows longer exposure of the same blot. Bottom panel shows reprobing of the same blot with an anti-S6 ribosomal protein antibody. (B) KT-1 cells were pre-incubated for 30 minutes with the indicated inhibitors and the cells were subsequently treated with IFNα. Top panel shows an immunoblot with an antibody against the phosphorylated form of the S6 ribosomal protein on serines 235/236. Middle panel shows longer exposure of the same blot. Bottom panel shows reprobing of the same blot with an anti-S6 ribosomal protein antibody. (C) Similar experiment to the one shown in panel B, except that IFNβ was used instead of IFNα. (D) KT-1 cells were treated with IFNα for different times, as indicated. Top panel shows an immunoblot with an antibody against the phosphorylated form of the S6 ribosomal protein on serines 240/244. Bottom panel shows reprobing of the same blot with an anti-S6 ribosomal protein antibody. (E) Similar experiment to the one shown in panel D, except that IFNβ was used instead of IFNα. (F) KT-1 cells were preincubated for 30 minutes in the presence or absence of LY294 002 or rapamycin, and were subsequently treated with IFNα, as indicated. Top panel shows an immunoblot with an antibody against the phosphorylated form of the S6 ribosomal protein on serines 240/244. Bottom panel shows reprobing of the same blot with an anti-S6 ribosomal protein antibody.