Briefly, after incubation of viable cells with the antibody or peptide for 30 min at 4uC and following two washing steps, viable cells were analyzed using a FACSCalibur flow cytometer. An isotype-matched control antibody was used to evaluate non-specific binding to cells. Breast cancer is the most common tumorigenic malignancy for women in Western countries and is the primary cause of mortality. Immunotherapy and targeting mammary-specific targets using antibodies or small molecules coupled with cytotoxic substances offer a good adjunct to standard protocols including surgery, cytotoxic drugs,Epimedin-A1 endocrine therapy and radiation therapy. Although new drugs are in development, the heterogeneity of cancer resulting from mutated genes, the differential expression of specific surface molecules, and/or the status of patients with regards to the stage and subtype of disease, makes it difficult to develop molecules and agents with broad specificity across individual patient groups. Interest in the use of peptides as agents for imaging and the specific delivery of therapeutic agents to tumors is therefore growing. Peptides offer a number of advantages such as better biodistribution profiles and Epimedin-C a greater ability to penetrate tissues. The efficacy of peptides for anti-cancer therapies is often dictated by their ease of binding and uptake into tumor cells. As examples, cathelicidin is been a potential therapeutic peptide for gastrointestinal inflammation and cancer and a 15-mer peptide from the follicle-stimulating hormone support the anti-tumor activity of paclitaxel nanoparticles against ovarian cancers. The cancerspecific peptide BR2 penetrates cancer cells, and has been shown to mediate the delivery of a scFv into cancer cells. The therapeutic capabilities of peptides have been demonstrated by a report of a peptide which is able to induce apoptosis in SKOV3 cells by down-regulating Bcl-2. The kinetics of peptide uptake has been studied in lymphocytes and monocytes. Interestingly, peptides have also been shown to facilitate the delivery of larger molecules. Nanostructured lipid carriers bound to small 5-mer peptides are taken up by EGFR-overexpressing tumors in vivo and such peptides might therefore support the targeted delivery of chemotherapeutic agents.