Stat1 mediates the antiproliferative effect in VSMCs in coculture. (A) VSMCs from Stat1^-/- and monocytes from wild-type mice were used for coculture and proliferation assay, as indicated in the legend to Figure 5. (B) Stat1si-VSMC with down-regulated expression of Stat1 (left panel) were used for coculture setting and proliferation assay (right panel). (C) VSMCs were microinjected with pSer727 Stat1 antibody and then cocultured. One hundred to 120 cells were microinjected in each experiment,; results shown are representative of 4 experiments. As a control, nonmicroinjected and nonspecific IgG-injected VSMCs were included. Microinjected and control cells were used for proliferation assay (left panel) and for immunocytochemistry (right panel).