Fig. 2

β₂AR signaling induces invadopodia formation. a LifeAct-GFP⁺ MDA-MB-231 cells were plated on Alexa-568-labelled gelatin and active invadopodia were identified by confocal microscopy as LifeAct-GFP⁺ puncta colocalized with degraded gelatin (loss of red fluorescence; see inset). Representative images are shown. Scale bar: 20 μm, or 5 μm for inset panel. b The frequency of invadopodia-positive cells was determined in cells treated with isoproterenol (Iso). c, d Cells were treated with 0.5 μM Iso ± 0.05 μM propranolol (Prop), and c the frequency of invadopodia-positive cells was determined or d the number of invadopodia per cell was determined (N >130 cells per treatment). e Cells were treated with Iso ± β₁AR-selective antagonist CGP-20712A (CGP) or β₂AR-selective antagonist ICI-118551 (ICI) and the effect on invadopodia formation was quantified. f, g Cells were treated with Iso, β₁AR-selective agonist xamoterol, or β₂AR-selective agonist formoterol and f the effect on invadopodia was quantified. g Representative confocal sections are shown. Inset shows GFP+ active invadopodia on degraded matrix (loss of red fluorescence). Scale bar: 20 μm, or 5 μm for inset panels. N > 80 cells per treatment unless otherwise stated. Experiments were conducted in triplicate. Error bars: SEM. *p <0.05, **p <0.01 and ***p <0.001