Cercosporamide suppresses phosphorylation of eIF4E. (A) U937 cells were incubated with cercosporamide (10 µM) for 24 hours. Cell lysates were resolved by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotted with an antibody against the phosphorylated form of eIF4E on serine 209. The same blot was stripped and reprobed with an antibody against eIF4E, as indicated. (B) MM6 cells were incubated with cercosporamide for 24 hours. Cell lysates were resolved by SDS-PAGE and immunoblotted with an antibody against the phosphorylated form of eIF4E on serine 209. The same blot was stripped and reprobed with an antibody against eIF4E, as indicated. (C) K562 cells were incubated with cercosporamide for 24 hours. Cell lysates were resolved by SDS-PAGE and immunoblotted with an antibody against the phosphorylated form of eIF4E on serine 209. The same blot was stripped and reprobed with an antibody against eIF4E, as indicated. (D) Serum-starved U937 cells were treated for 1 hour with increasing doses of cercosporamide, as indicated. Lysates were resolved by SDS-PAGE and immunoblotted with an antibody against the phosphorylated form of eIF4E on serine 209. The same blot was striped and reprobed with an antibody against eIF4E, as indicated. ser, serine.