CD3 (Cluster of differentiation 3), originally known as T3, is one of the first groups of human T lymphocyte surface antigens recognized by monoclonal antibodies. It has been reported that antibodies against CD3 could either stimulate T cells to divide or inhibit the progress of effector functions according to the conditions used. It plays an important role in T cell and the CD3 T-cell co-receptor helps to activate the cytotoxic T-Cell and T helper cells. The CD3 molecule is composed of a protein complex and consists of four distinct chains. The complex of mammals contains a CD3γ chain, a CD3δ chain, and two CD3ε chains. All these chains associate with T-cell receptor and the ζ-chain to generate an activation signal in T lymphocytes. MUC1 (Mucin 1, cell surface associated), also referred to tumor-associated epithelial membrane antigen, EMA, MCD or CD227, is a 122 kDa single-pass type I transmembrane protein mapping at the chromosome 1q22. It is generally expressed on glandular or luminal epithelial cells of the mammary gland, stomach, esophagus, duodenum, pancreas, prostate, uterus, and lungs, and lesser in hematopoietic cells, but absent in the skin epithelium and mesenchymal cells. MUC1 gene coding for a membrane-bound protein, a member of the mucin family, is an O-glycosylated protein that functions in forming protective mucous barriers on epithelial cell surfaces. And they also play a part in intracellular signaling. Abnormally glycosylated MUC1 is overexpressed in most human epithelial cancer cells and has been regarded as an oncogenic molecule.