The upstream regulatory region of the c‐fos promoter contains two growth factor‐regulated promoter elements: the serum response element, which binds a ternary complex comprising serum response factor (SRF) and a ternary complex factor (TCF); and the sis‐inducible element (SIE) which binds STAT transcription factors. We used transient transfection of c‐fos promoter mutants in NIH 3T3 cells to assess the contributions of these elements to activation by different extracellular stimuli. Colony‐stimulating factor‐1, platelet‐derived growth factor and epidermal growth factor activate the c‐fos promoter via cooperation of the SIE and the SRE; however, mutants that can bind SRF but not STATs or TCF remain inducible by whole serum. Activation by the SIE is context‐dependent: interferons activate STAT DNA binding activity and transcription of SIE reporter genes, but not the c‐fos promoter, which requires an additional ras‐dependent signal. SRE activation by receptor tyrosine kinases requires TCF binding, and can be mediated by the TCF Elk‐1. In contrast, SRE activation following activation of heterotrimeric G proteins by lysophosphatidic acid or aluminium fluoride ion requires SRF but is independent of TCF binding. These results suggest that heterotrimeric G proteins activate a signalling pathway distinct from those that activate the STATs and the TCFs, that controls SRF activity.