Specificity and sensitivity of the Phospho-p44/42 MAPK (Erk1/2) (Thr202/Tyr204) (E10) Mouse mAb: This antibody reacts specifically with as little as 50 pg of phosphorylated MAP kinase and does not cross-react with up to 4 µg of nonphosphorylated MAP kinase by Western blotting.