tPA-binding to injured neurons is specific and occurs via the F, E, or K1 domains. (A) Increasing amounts of tPA⁶³³ were transiently perfused over neuronal cultures. Plotted is the binding of tPA⁶³³ to a single dead neuron over time (circled in the micrograph where tPA⁶³³ fluorescence is depicted in red). (B) tPA⁶³³ (1 nM) was perfused over neuronal cultures either alone (“no competitor”) or with various competitors. For a single experiment, the average relative amount of tPA⁶³³ binding was determined for all nonviable cells in a field. Shown are collated data from n = 3 to 7 independent experiments. Data represent average ± SEM. *P < .05 by 1-way ANOVA with Neumann-Keuls correction.