Figure 2: Affinity labeling of SDT with RTI-63 using UV or X-rays. While UV affects affinity labeling of SDT ( , ) in a manner related to RTI-63 concentration ( , ), no significant dose-related binding is identified with respect to X-ray dose (11–31 cGy) or to RTI-63 concentrations (100–2000 nM). The largest magnitude of gamma-rays-induced binding occurs with RTI-63 at 100 nM ( , ).