In addition to validation of aptamers via surface plasmon resonance (SPR), we have successfully employed aptamers in fluorescence activated cell sorting (FACS) with collaborators at nearby M.D. Anderson Cancer Center (Houston, TX). The Center’s scientists used our aptamers to label and differentiate a panel of recombinant proteins expressed on desired T-cell subsets. Results were generated using flow cytometry. Aptamers provided an effective alternative to monoclonal antibodies (mAbs) in this application, producing inexpensive cellular reagents in line with current good manufacturing practice (cGMP).