There is increasing interest in the application of gene induction measurement techniques to many aspects of biology and in particular, pharmacology and toxicology. Phase 1 Molecular Toxicology Inc is developing a range of assays using technology specifically designed for high throughput screening and molecular end-points of demonstrable relevance both in terms of mechanisms of toxicological damage and to the more complex, "traditional" toxicology assays. The use of Amersham Biosciences 96 well scintillating Cytostar microplates has allowed large numbers of compounds to be screened against cell lines and the induction of panels of genes of interest to be measured, rapidly. However, the interpretation of gene induction measurements in vitro must be made in the context of other molecular activities within the cell and with reference to dose and time effects, to avoid misinterpretation of the effects of compounds.