Fig. 7. Time-lapse sequences of ruffling and macropinocytosis. Macrophages were stimulated with 2000 U ml^-1 M-CSF and treated with 0.1% dimethyl sulfoxide (control; A), 100 nM wortmannin (B), 10 µM ML-7 (C) or 10 µM cytochalasin D (D). Numbers indicate time sequence with 10-second intervals. Ruffles were seen as phase-dense bands in the periphery of the cells. (A) In control cells, phase-bright macropinosomes were formed by closing circular ruffles (arrows). (B) Wortmannin did not inhibit circular ruffle formation but did inhibit the closure of circular ruffles into macropinosomes (arrows). (C) In ML-7, ruffle movement was markedly reduced. No circular ruffle formation was observed. Only simple centripetal movement of ruffles was seen. (D) Cytochalasin D stopped the ruffle movement completely. Bar, 10 µm. The supplemental video materials are available in the online version [Video 2 (http://www.jcs.biologists.org/supplemental)].