We explored the molecular basis of the markedly reduced CYT387 autolytic phenotype and biofilm inhibition triggered by MOL using transcriptomic analysis and we verified the transcription of autolysis-related genes by real-time RT-PCR. GeneChip analysis revealed that a large number of genes were differentially regulated in response to sub-inhibitory concentrations of MOL. Two hundred ten genes showed significant increases and 340 genes showed significant decreases in transcription. The microarray data were submitted to Gene Expression Omnibus under the accession number GSE 13236, and a complete list of all genes that were differentially expressed following MOL treatment can be found in the supplementary material . We compared the genes that were differentially regulated by MOL treatment with those identified in previous S. aureus global transcriptional profiles ; our interest was mainly focused on autolysis-, biofilm- and virulence-associated genes involved in the response to MOL. We analyzed the expression levels of 77 genes involved in autolysis or related regulators using a microarray , and we compared the 106 genes involved in biofilms in previously reported microarray results with counterparts in our result . A small subset of those transcripts was also evaluated by real-time RT-PCR . Microarray results showed that transcript levels of the main autolysin genes atl, sle1 and cidA significantly decreased by a factor of 3.3, 10.9 and 3.3, respectively, and transcript levels of lytM and lytN were slightly decreased. The expression levels of the negative regulators of autolysis lrgA, lrgB, arlR and sarA were significantly increased by 35.0-, 30.9-, 2.0- and 3.1-fold, respectively. Reduced atl, sle1 and cidA transcript levels were consistent with the induced expression of their autolytic repressors lrgA, lrgB, arlR and sarA in the MOL-treated Masitinib VEGFR/PDGFR inhibitor strain compared with the control strain, which individually or collectively may contribute to the autolysisinhibited phenotype according to previous studies . Realtime RT-PCR confirmed the decreases in atl, sle1, cidA, lytM and lytN levels and the increases in lrgA, lrgB, arlR and sarA levels . Surprisingly, the transcript levels of the autolysin genes cidBC were significantly increased. The cidB and cidC genes are also co-expressed as a transcript separate from cidABC, and this cidBC transcript is regulated by signals that are independent of cidABC regulation . This mechanism could explain why the microarray showed upregulation of cidB and cidC and downregulation of cidA. The microarray data showing changes in cidBC, agrA, RNAIII, lytR and lytS transcript levels in strain ATCC 25923 exposed to the same concentration of MOL were confirmed by real-time RT-PCR; there were also no significant changes in mgrA and arlS levels . SA0904, which encodes a probable