Fig 1.

HSP70 overexpression represses activity of the c-fos promoter under basal conditions as well as under Ras-activation in vitro. (A) CHO-K1 cells transfected with c-fos promoter reporter plasmid pfos396D219-81 were cotransfected with either 50 ng/well human-HSP70 (HSP70), 50 ng/well human-HSF1 (HSF1) expression plasmids, or empty vector (pcDNA3.1(−)) with or without cotransfection of Ras (100 ng/ml) expression plasmid or vector (100 ng/ml). Cells were harvested 16 to 20 hours after transfection, and whole-cell extracts were subjected to luciferase assay. Bars represent mean relative luciferase activity ± standard deviation and show results from 3 independently performed experiments. (B) A constant amount of Ras (100 ng/well) and c-fos reporter (250 ng/well) were cotransfected with increasing doses of HSP70 expression plasmid, and whole-cell extracts were then subjected to Luciferase assay. Cells were harvested 16 to 20 hours after transfection, and whole-cell extracts were subjected to luciferase assay. Bars represent mean relative luciferase activity ± standard deviation and show results from 3 independently performed experiments