FIG. 4.
Effects of various GEFs for Ras-like GTPases on EGF-induced PLC and Ca2+ signaling. (A to C) HEK-293 cells were transfected with empty vector (Vector, V), PDZ, C3G, Epac1, Repac, GRP2, RasGRP1, or RasGRP3 (25 μg of DNA each). At 48 h after transfection, levels of IP3 formation measured for 1 min in the absence (Basal) or presence of 100 ng of EGF/ml (B) and EGF-induced [Ca2+]i increases (C) were determined. (A) Immunoblot detection of the HA-tagged GEFs in lysates of transfected cells. Inset in panel B: immunoblot detection of C3G. (D) Detection of RasGRPs in HEK-293 cells by reverse transcriptase PCR (RT-PCR). Data in panel B represent means ± SEM (n = 3 to 5); in panel C, superimposed tracings of [Ca2+]i are shown.