It has been demonstrated that RasGRF1 is a c-Jun-regulated gene necessary for promoting non-adherent growth of c-Myc- or c-Jun-transduced fibroblasts and not much attention has been paid to a potential role of RasGRF1 in tumorigenesis, despite this protein having been observed to be expressed in several tumor types (48). This evidence concerns the gene JUN and neoplasm.