A Nature Structural & Molecular Biology article published by Singer et al has provided a fascinating insight into the kinetics of RNA polymerase II during transcription. Using a combination of extremely elegant fluorescent microscopy-based assays and computer modelling, the group have provided the first measurements of RNA polymerase II kinetics in living cells. Among their findings are that only 8% the RNA polymerase/promoter interactions lead to mRNA synthesis and that the elongation speed of the polymerase is much faster than previously thought. This is a remarkable piece of experimental design and is well worth reading.