PDPN and breast cancer: It is a novel monoclonal antibody to an Mr 40000 O-linked sialoglycoprotein that reacts with a fixation-resistant epitope on the lymphatic endothelium [16] The D2-40 antibody has been shown to specifically recognize podoplanin, a glomerular podocyte membrane protein [17,18] and has been shown to be a very sensitive and specific marker for lymphatic endothelium in most tissues [19] and especially in breast cancer [20].