LERD inhibits the activation of Syk and Syk-mediated downstream signaling molecules. The RBL-2H3 cells (upper panel) or BMMCs (lower panel) were incubated overnight with 50 ng/ml IgE and cells were then stimulated with 25 ng/ml antigen with or without LERD for 7 min. Cell lysates were subjected to immunoblot analysis with specific antibodies to detect phosphorylated or total proteins. Representative immunoblotting images are shown from three independent experiments. PP2 is a general Src family kinase inhibitor.