biostudies-literatureUnknown15(6)Takaya ARalA, a member of the Ras-family GTPases, regulates various cellular functions such as filopodia formation, endocytosis, and exocytosis. On epidermal growth factor (EGF) stimulation, activated Ras recruits guanine nucleotide exchange factors (GEFs) for RalA, followed by RalA activation. By using fluorescence resonance energy transfer-based probes for RalA activity, we found that the EGF-induced RalA activation in Cos7 cells was restricted at the EGF-induced nascent lamellipodia, whereas under a similar condition both Ras activation and Ras-dependent translocation of Ral GEFs occurred more diffusely at the plasma membrane. This EGF-induced RalA activation was not observed when lamellipodial protrusion was suppressed by a dominant negative mutant of Rac1, a GTPase-activating protein for Cdc4Molecular biology of the cell2549-57https://www.ebi.ac.uk/biostudies/studies/S-EPMC420081biostudies-literatureRalA activation at nascent lamellipodia of epidermal growth factor-stimulated Cos7 cells and migrating Madin-Darby canine kidney cells.PMC420081Ohba YTakaya AKurokawa KMatsuda MfalseRalA activation at nascent lamellipodia of epidermal growth factor-stimulated Cos7 cells and migrating Madin-Darby canine kidney cells.RalA, a member of the Ras-family GTPases, regulates various cellular functions such as filopodia formation, endocytosis, and exocytosis. On epidermal growth factor (EGF) stimulation, activated Ras recruits guanine nucleotide exchange factors (GEFs) for RalA, followed by RalA activation. By using fluorescence resonance energy transfer-based probes for RalA activity, we found that the EGF-induced RalA activation in Cos7 cells was restricted at the EGF-induced nascent lamellipodia, whereas under a similar condition both Ras activation and Ras-dependent translocation of Ral GEFs occurred more diffusely at the plasma membrane. This EGF-induced RalA activation was not observed when lamellipodial protrusion was suppressed by a dominant negative mutant of Rac1, a GTPase-activating protein for Cdc42004-01-01T00:00:00Z2004 Jun2025-05-29T16:01:00.873Z2025-05-29T16:01:00.873ZS-EPMC4200811503414210.1091/mbc.e03-11-0857