Okadaic Acid inhibits PP2A in 3T3-L1 cells. Cells were grown to 70% confluence and serum starved for 18 h. For in vivo phosphatase activity, the growth medium was replaced with HENK?s and the cells were preincubated in the presence or absence of 100 nM Okadaic Acid (ammonium salt) (ab141830), (or Okadaic Acid (sodium salt) (ab141831)) and 100 nM 1-Norokadaone (ab145527) followed by a 20 min incubation with or without 20 µM NEM. The cells were then stimulated with 5 ng/ml PDGF for 30 min. At the end of the incubation, cell proteins were resolved by SDS-PAGE and probed with anti-phospho-Akt antibodies.