Eukaryotes transcribe much of their genomes, but little is known about the fidelity of transcriptional initiation by RNA polymerase II in vivo VSports手机版. I suggest that 90% of Pol II initiation events in yeast represent transcriptional noise, and that the specificity of initiation is comparable to that of DNA-binding proteins and other biological processes. This emphasizes the need to develop criteria that distinguish transcriptional noise from transcription with a biological function. .