C. Representative image for U-2-OS 263 IFII cells harbouring the reporter construct and transfected with the siRNAs indicated. After addition of doxycycline, transcription was monitored in cells ± induction of FokI by quantification of YFP(-MS2) foci. Arrows indicate sites of FokI mediated DSB (mCherry) and YFP-MS2 transcript. "TRXN": doxycycline added; "TRXN/DSB": doxycycline added with 4-OHT. Scale bar is 10 μm 