Does Herceptin prevent dimerization of the HER-2 receptor or does it just prevent cell signalling?

"Not sure, I know it's a monoclonal antibody, and I pretty sure that it prevents receptor dimerization of HER-2 receptor and therefore signalling. (Wow haven't thought of Tyrosine kinase signalling for awhile...). Here's an article http://theoncologist.alphamedpress.org/cgi/content/full/9/suppl_3/4 Good question."