Fig. 3. PHB2 represses the transcriptional activity of MyoD and MEF2. C2C12 cells were separately co-transfected with 3xMEF2-luc (A), 4RE-luc (B) or gal4-luc (C), together with various expression vectors as indicated. After 36 hours of growth in GM and 24 hours in DM, cells were harvested and the luciferase activity in each sample was determined. Fold change was calculated as the ratio of the luciferase activity in samples transfected with either PHB2 (A,B) or Gal4MEF2/Gal4-MyoD with or without PHB2 (C) to that of samples transfected with either an empty vector (A,B) or Gal4DBD (C). Abbreviations: DBD, DNA-binding domain (amino acids 1-147 of Gal4); vec, an empty vector. All experiments were done independently three times and the results were presented as mean±s.d.