PDGF-stimulated CDR formation and macropinocytosis in PIK3CB KO NIH3T3 cells. PIK3CB KO NIH3T3 cells were seeded in MatTek dishes and serum-starved overnight. Time lapse images were acquired at 1 frame/10 sec, for a total duration of 30 minutes. PDGF was added after 1 min. The replay speed is 3 min/s.