The c-kit receptor clusters on the cell surface within 3 minutes of exposure to SCF. MO7e cells were exposed to SCF (200 ng/mL) for 0 minutes (A and B), 3 minutes (C and D), or 30 minutes (E and F) at 37°C. One portion of each aliquot of cells was stained with 104D2 followed by goat antimouse IgG-FITC to detect cell surfacec-kit receptor (A, C, and E). The other portion of each aliquot of cells was permeabilized with Triton X-100 to permit detection of intracellular c-kit receptor in addition to cell surfacec-kit receptor (B, D, and F), then stained as described above. The cells were analyzed by confocal microscopy.