CSF-1 generates oscillatory activation of AKT and ERK1/2. (A-E) Human monocytes were exposed for indicated times to 100 ng/mL CSF-1 before immunoblot analysis of indicated proteins, with p indicating phosphorylated proteins. One representative of 5 independent experiments is shown. (C-D) Ratio of phosphorylated ERK1/2 and phosphorylated AKT, respectively, to the corresponding total protein level measured by analysis of the blots with ImageJ software. (F) Monocytes were exposed to CSF-1 in the absence (left) or presence of U0 (U0126, 10 μmol/L, right), or LY (LY294002, 10 μmol/L, middle) added to the culture medium 30 minutes before CSF-1, and the expression of indicated proteins was analyzed by immunoblot at indicated time points. Molecular weight (MW) is given in kilodaltons. *Cleavage fragments.