Gene expression is regulated via proteins called transcription factors and nuclear receptors that bind to specific regulatory sequences in DNA, thereby modulating the transcription of genes into RNA. These proteins are often present in the cell in an inactive form, and only become activated to bind to their cognate recognition sequences as a result of a specific signal transduction event. xMAP® Technology provides a powerful approach for multiplex detection of activated transcription factors, allowing researchers to simultaneously measure the binding of many different transcription factors at once in a single sample. Results can be obtained in a few hours, allowing hundreds of samples to be analyzed in a day. Excellent sensitivity, dynamic range and reproducibility are routinely achieved. Such assays are appropriate for research in many scientific disciplines, providing a powerful technology for elucidating mechanisms of gene regulation, identifying drug targets, screening lead compounds and proteomics research.