Proximity ligation assay (PLA) was performed using the anti-Mouse MINUS probe, anti-Rabbit PLUS probe and the orange detection reagent (Sigma-Aldrich) as previously described(53 (link)). Actin was visualized using actistain 670 and imaged on a Leica scanning confocal (SP5) with a HCX Plan Apochromat 63×/1.40–0.60 NA oil λ blue objective. The total number of distinct PLA spots per cell were quantified using the threshold function of ImageJ.