By pretreating breast cancer cells with a cross-linking reagent such as anti-CD44 antibody, Wang et al [15] reported that ligation of tumor cell surface CD44 enhanced tumor cell transendothelial migration by increasing the expression of lymphocyte function-associated antigen-1 (LFA-1) and very late antigen 4 (VLA-4). Here, CD44 is linked to breast carcinoma.