ABSTRACT
OMICS (Box 1) approaches such as genomics and transcriptomics have made it possible to study gene expression profi les in cells, tissue, and organism after exposure to toxic compounds. But the expression profi les generated from these studies do not necessary refl ect the protein expression profi les. In higher organisms protein expression is highly regulated and a linear correlation between mRNA levels and corresponding protein expression may not be found. The stability of mRNA, protein accumulation and degradation, and a huge number of possible protein post-translational modifi cations of proteins are among factors that can contribute to this difference. To fully understand the molecular action of toxins we must elucidate their effect upon proteins, and in particular proteins belonging to cell signaling pathways, by proteomic approaches. Proteomics includes identifi cation and determination of changes in proteins expressed in a cell type, tissue, or organism (its proteome), and how these proteins function and interact with each other (Box 1).
