Adenosine induces the normal activation of Akt, ERK, and p38 MAP kinase in

syk^−/− bone marrow–derived mast cells. Wild-type and syk^−/− BMMCs were stimulated with 10 mM adenosine (A) or 0.5 μg/mL anti–DNP IgE followed by DNP-HSA (B) for the indicated amounts of time. Cell lysates were analyzed by SDS-PAGE followed by immunoblotting with anti–phospho-Akt, anti–phospho-ERK, and anti–phospho-p38 MAP kinase. Equal expression of Akt, ERK, and p38 MAP kinase was confirmed by probing the same immunoblots with appropriate antibodies.