There is a high correlation between a chemical's ability to induce DNA damage and its ability to cause cancer. For this reason, it is crucial to rapidly identify substances which have the ability to damage DNA. We have adopted a genomics approach to better understand how the model organism Saccharomyces cerevisiae senses and responds to DNA damage, hoping that further elucidation of these complex pathways will lead to the design of improved methods for sensing and reporting the presence of a potential carcinogen. An ideal assay would not only identify when DNA damage is occurring, but report what type of damage is taking place (eg. single- or double-stranded damage) as well as quantifying the amount of damage that has occurred. In this work, photolithographic microarrays were used to quantify changes in the S. cerevisiae trancriptome in response to multiple types of DNA damage. This genome wide screen identified HUG1 as a gene that is highly induced by many types of DNA damage. This result led us to create a fusion in which the HUG1 promoter regulated expression of green fluorescent protein (GFP), creating a cell strain which produced detectable levels of fluorescence when DNA damage occurred. To yield a positive result (ie. conclude that DNA damage was occurring), GFP levels as measured by flow cytometry had to increase at least 2-fold over control cells not exposed to genotoxicity, with a p-value less than or equal to 0.05. These new cell lines allowed us to measure gene expression patterns in real-time in response to multiple cellular stresses, including genotoxicity. This ability enabled us to identify DNA damage response pathways that are differentially regulated based on the type of insult that has occurred, in a manner that is simpler and cheaper than traditional methods.