A pair of Clontech microarrays hybridized as described in Materials and methods to mRNA from cultured rat mesothelioma cells. (a) Control expression patterns. (b) Expression patterns from cells after treatment with potassium bromate. Waf-1 and HSP-70 are examples of genes that seem to be upregulated as a result of potassium bromate treatment. Note the apparently consistent overall expression pattern from one array to the other, in spite of the toxic treatment received in (b).