Fig. 7. Transient aggregation of CHO-CD47 and CHO–SHPS-1 cells. (A) CHO–SHPS-1 cells were mixed with CHO-CD47 cells, incubated for the indicated times, fixed, and examined by phase-contrast microscopy. Bar, 20 µm. (B,C) CHO–SHPS-1, CHO–SHPS-1–C404, or CHO-Ras cells were mixed with CHO-CD47 cells and incubated for the indicated times (B). Alternatively, CHO–SHPS-1 cells were pretreated with 0.5 µM cytochalasin D or DMSO for 30 minutes, mixed with CHO-CD47 cells or control CHO-Ras cells, and incubated for the indicated times (C). Cells were then fixed and the extent of cell aggregation was quantified as the ratio of the number of cells at the indicated time (N_t) to that at the initiation of incubation (N_o) as described in Materials and Methods. Data are means ± s.e.m. from three separate experiments. ^*P<0.05, ^**P<0.01 versus the corresponding value for CHO–SHPS-1 cells (B) or DMSO-pretreated cells (C).