Previously we have reported that the O-methylated derivative of (-)-epigallocatechin-3-O-gallate (EGCG), (-)-epigallocatechin-3-O(3-O-methyl) gallate (EGCG3"Me), possesses anti-allergic activities such as inhibition of histamine release and suppression of the high-affinity IgE receptor (Fc epsilon RI) expression. However, the underlying mechanism is still unclear. Recently we have identified the 67 kDa laminin receptor (67LR) as a cell-surface receptor that can mediate biological activities of EGCG. Here we show that the suppression of myosin II regulatory light chain (MRLC) phosphorylation through the cell-surface binding to the 67 LR contributes to the inhibitory effect of EGCG3"Me on the histamine release from the human basophilic KU812 cells. The 67LR also mediated the EGCG3"Me-induced suppression of Fc epsilon RI expression by reducing ERK1/2 phosphorylation. These results suggest that anti-allergic effects of EGCG3"Me may be triggered by the inhibition of MRLC or ERK1/2 phosphorylation mediated through the cell-surface 67LR. (C) 2007 Elsevier Inc. All rights reserved.