Microarrays are being used in cancer research with incredible results. For example, researchers used microarrays to compare gene activity patterns in normal stomach tissue and tissue from stomach tumors. They found that the tumor tissue, but not the normal tissue, expressed a gene called PLA2G2A. But they also found that cancer patients with high expression levels of PLA2G2A were more likely to survive for 5 years, compared with patients whose tumors produced lower levels.