Ready-to-use ELISA kits are available for the detection of W3/25, an alias of the protein, CD4 molecule. The official gene symbol is CD4. The protein, with a mass of 51.1 kDa and length of 458 residues, is reported to be membrane-associated. It may be known by other names, including: T-cell surface antigen T4/Leu-3, CD4 receptor, CD4 antigen (p55), and T-cell surface glycoprotein CD4.