Figure 4

Brn-3b promoter is activated via the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway in breast cancer cells. (a) Brn-3b promoter activity is shown following treatment of transfected cells with inhibitors of different signalling pathways (as indicated), in absence or presence of NGF or EGF. Values have been adjusted using internal Renilla luciferase control and represent means ± SD of at least three independent experiments. (b) Increase in Brn-3b promoter activity following treatment of transfected cells with the protein kinase C analogue phorbol 12,13-dibutyrate in the absence or presence of the ERK inhibitor, PD98059. Values represent relative luciferase activity after adjusting for Renilla internal control. (c) Brn-3b promoter activity is shown following cotransfection with either dominant-negative mitogen-activated protein kinase kinase (dnMEK) or WT MEK compared with activity in the presence of the ERK inhibitor PD98059. Values represent relative luciferase activity after adjusting for Renilla internal control.