CD4 (1F6) is a glycoprotein belonging to the immunoglobulin superfamily that is expressed on the surface of T-helper cells, thymocytes, and some monocytes, as well as Kupffer cells and endothelial cells of the liver. It is positive in most cutaneous T-cell lymphomas, mycosis fungoides, anaplastic large cell lymphomas and HTLV-1 associated adult T-cell leukemias and lymphomas. It is negative for staining in NK cells and B-cell lymphomas. References: Article ID 925135, 12 pages, doi:10.1155/2012/925135