AMPK activation stimulates production of PIP3. 3T3-F44a preadipocytes bearing empty lentiviral vector (A) or the dominant negative mutant of AMPKα1 subunit (B) were treated with AICAR (1 mM, 4 h) or insulin (100 nM, 15 min). Cells were immunostained with anti-PIP3 monoclonal IgM antibody and counter-stained with DAPI for visualization of cell nuclei. Cells with empty viral vector accumulated PIP3 when treated with AICAR, as well as insulin (A). The AICAR induced PIP3 accumulation was not seen in the cells containing the AMPK mutant, whereas the effect of insulin was not affected (B). Scale bar: 63.4 μm.