HeLa cells transiently transfected with PCNA-mRFP and Tom70-eGFP were subjected to one-step immunostaining with RFP-Booster Alexa Fluor 568 (red) and GFP-Booster Alexa Fluor 488 (green). Scale bar, 10 μm. Images were recorded at the Core Facility Bioimaging at the Biomedical Center, LMU Munich.