Diazaborine inhibits maturation of rRNAs for the large ribosomal subunit. Diazaborine blocks ribosome biogenesis by inhibiting the AAA-ATPase Drg1. Diazaborine treatment causes, within minutes, a rapid redistribution of the protein from the nucleolus to the periphery of the nucleus, which provides a possible explanation for the effect of diazaborine on rRNA processing.