Activation of the c-fos promoter by M-Ras; evidence for sharing of effectors with p21 Ras. Shown are relative luciferase units derived from assays of lysates of 293-cells transiently transfected with 0.25 μg of the c-fos luciferase reporter plasmid and: (A) 3 μg of the indicated plasmids; (B) 0.25 μg of a N-Ras Q16K plasmid and the indicated amounts of M-Ras G22V plasmids. Results represent data from 6 (A) or 3 (B) independent experiments and are shown as mean ± SD. All transient transfections contained equal amounts of total plasmid DNA, normalized with empty vector containing the same promoter. The lower panel of (B) shows results of a cell-fractionation experiment. Lysates of N-terminally tagged M-Ras G22V or C-terminally tagged M-Ras G22V (CTm) were subjected to ultra-centrifugation. Samples of whole-cell lysate (wcl), the membrane-enriched fraction (m) and the cytosolic fraction (c) were separated on SDS-PAGE and immunoblotted with anti–myc-epitope antibody 9E10.