Dimerization of the c-kit receptor is detectable within 3 minutes after the addition of SCF. MO7e cells were labeled with 104D2-FITC plus 104D2-Cy3 for 45 minutes at 4°C, then incubated in the absence (•) or presence (○) of SCF (200 ng/mL) for 3 minutes, 10 minutes, 30 minutes, or 60 minutes at 37°C, fixed, and analyzed as described in Table 2. Two additional experiments gave similar results. Analysis of variance with a post hoc Student'st-test was used to determine if the acceptor/donor ratios at the various time points in the three experiments were different than the values at time 0. In the presence of SCF, the acceptor/donor ratios at 3 minutes, 10 minutes, 30 minutes, and 60 minutes were different than the acceptor/donor ratio at time 0 (P < .05).