SAP18 is a highly evolutionarily conserved protein found in all eukaryotic organisms from Saccharomycces cerevisiae to humans. It has been proposed to be involved in multiple cellular processes, from gene regulation to mRNA processing, playing different cellular functions, such as cell fate control during development or regulation of apoptosis or salt stress responses. Previous studies found SAP18 capable of repressing transcription when tethered directly to a promoter region. To gain further insight into the role of Drosophila SAP18, we performed genome-wide expression profiling of a dSAP18 mutant allele and found that dSAP18 is required for the expression of several immune-related genes, amongst others. To provide an updated view of the transcriptome, the probe sequences from the platform used (GPL3797) were matched to FlyBase Genome Release 5.5 and the corresponding gene names and identifiers were obtained. In the cases where one probe matched more than one gene, all of them were obtained. A total of four microarrays were hybridized in biological replicate pairs, such that the total RNA from dsap18 mutant animals (dsap18^117/Df(3R)sbd^45 0-24h staged embryos) and control animals (rescued dsap18^117/Df(3R)sbd^45 0-24h embryos containing a dsap18-HA transgene) used as starting material came from different extractions. Both arrays from each pair were hybridized with the same amplified RNA from sample and common reference (obtained using the Amino-Allyl Messageamp II aRNA Amplification Kit from Ambion, Inc) but with dyes (Cy3 and Cy5 from Amersham, Inc) swapped to take dye-bias into account.