Figure 5.

LPS stimulation transiently activates STAT3 in raw 264.7 macrophages. Expression of SOCS3 was increased only after 18 h of LPS stimulation (a). Coimmunoprecipitation indicates a dynamic direct physical interaction between SOCS3 and STAT3 in murine macrophages. Raw 264.7 cells were stimulated with LPS (or the same volume of PBS vehicle) for 10 and 60 min. SOCS3 was immunoprecipitated from 500 ug of cell lysates, and after electrophoretic separation (SDS-PAGE), STAT3 was detected by western blotting. “Input” indicates the same quantity of cell lysate loaded onto “empty” affinity columns (no primary antibody immobilized), and “IgG” represents columns in which the same quantity of irrelevant IgG from rabbit was immobilized in the columns. Image is representative of three independent experiments.