Homologous recombination DR-GFP assay
48 hours after siRNA transfection, U2OS DR-GFP cells 16 were co-transfected using Amaxa nucleofection with an I-SceI expression vector (pCMV-I-SceI) and a vector expressing mCherry fluorescent protein (pmCherry-C1). 24 hours after I-SceI transfection cells were harvested and analysed by flow cytometry (CyAn ADP Analyzer, Beckman Coulter). The percentage of GFP-positive cells among transfected cells (mCherry-positive cells) was determined using Summit 4.3 software. siControl treated sample was set as 100%. Statistical significance was determined with the Student’s t-test.