Copyright information:Taken from "An SOS-regulated operon involved in damage-inducible mutagenesis in "Nucleic Acids Research 2005;33(8):2603-2614.Published online 10 May 2005PMCID:PMC1092274.© The Author 2005. Published by Oxford University Press. All rights reserved Nucleotides 1557–1625, comprising the cluster II of rifampicin resistance, are shown in this figure. All mutants analyzed had mutations in this region of the gene. Mutations in shaded background correspond to repetitions of the same base substitution, and tandem mutations are underlined. The total number of independent mutations sequenced is indicated for each strain.