CD28 and melanoma: To evaluate the in vivo therapeutic potential of the recognition-then-activation model, a LD201t1/PD-L1 c-bsApt (Figure 3A) was also tested in a B16-F10 (murine melanoma) tumor model, where combination of this c-bsApt with anti-CD-28 antibody-coated T cell activator beads showed decreased tumor growth and increased survival compared with controls.