eXpress™ Assay Kits
Discovery Stage Cell-Based Assays for Determining Proof-of-Concept, MOA Confirmation, and Rank-Ordering Studies
eXpress Assay kits developed by Eurofins DiscoverX® are ready-to-use (RTU) cell-based assay kits for functional mechanism of action (MOA) or binding assay for drug discovery target validation, screening and hit ID, and lead optimization applications.
Each assay kit includes RTU cryopreserved cells, optimized assay reagents, plates, and a detailed assay protocol to ensure robust and reliable performance every time. By eliminating lengthy, time-consuming, and expensive cell culture steps, eXpress assay kits enable you to screen your small molecule or biologic therapeutics and generate accurate, precise, and reproducible functional data in just a few hours.
Eurofins DiscoverX offers over 1,000 target-specific eXpress assay kits for a broad range of target classes, including GPCRs, kinases, cytokine/interleukin receptors, checkpoint receptors, NHRs, epigenetic proteins, and more. The homogeneous assay kit format allows you to detect agonists, antagonists, and allosteric modulators. Their chemiluminescent read-outs can be read on any standard benchtop luminometer to provide fast and reliable results. Simply thaw, plate, and run the assay! Minimize assay development time and eliminate the need for cell culture.
Product Highlights
- Target Characterization - Identify targets and validate distinguishing target-specific variations like species, orthologs, isotype, and more during early drug discovery programs
- Functional and Binding Analysis - Perform quick, high-throughput cell-based assay binding and mechanism-of-action (MOA) assessment of your small molecule compounds or biologics
- Screening and Hit Identification - Identify hits; run primary, secondary and orthogonal screens; and rank-order hits
- Lead Optimization - Define best leads; optimize lead potencies, efficacy, and specificity; and perform SAR and ligand bias studies
- All eXpress Assay Kits – Quick analysis eXpress assay kits are based on the Eurofins DiscoverX Enzyme Fragment Complementation (EFC) platform, are available in 96-well 2-plate and 10-plate kits formats, and includes cells, optimized reagents, and plates for convenience
- InCELL Hunter eXpress Kits – Determine compound entry and target engagement (binding) to intracellular kinase and epigenetic protein targets
- GPCR eXpress Kits – Assess GPCR recruitment of β-arrestin, accumulation of cAMP, or internalization of GPCRs
- Checkpoint Receptor Products – Analyze dimerization of TIM3/TIM3 and VISTA/VISTA checkpoint receptors
- Cytokines and Interleukin Receptor Products – Determine receptor activation (SH2-recruitment) and dimerization assessment of several cytokines and interleukin receptors
- Kinase Product Solutions – Assess intracellular kinase compound entry and target engagement (binding) and receptor tyrosine kinase (RTK) activation (SH2-recruitment)
- Signaling Pathway Products – Analyze protein binding of Bcl2L1-Bax, degradation of CD25A or NFκB, or nuclear translocation of Keap1-NRF2, NFκB, PI3, SERBP2, TORC, Wnt-FzGSK3β or XBP1

The robust and reliable eXpress assay cells give similar results as continuous culture cell lines. Measurement of GPCR β-arrestin recruitment by the CNR1 receptor in response to increasing concentrations of ligand CP 55,940 using PathHunter® eXpress assay cells (A.) or the cell line (B.). Results demonstrate that eXpress assay cells have similar signal-to-background (S/B) and EC50 values compared to the dividing, continuous culture cells demonstrating the robust and reliable nature of the eXpress assay cells format.

eXpress assay kits produce highly reproducible results. One vial each of three different lots of PathHunter TrkA Functional Assay eXpress assay cells were thawed and plated into 96-well dishes on 3 separate days and assay performance was compared. Similar S/B and EC50 values were obtained showing that the eXpress format produces highly reproducible results every time.

eXpress assay kits are adapatable to miniaturization. eXpress cells expressing the GPCR Bradykinin B1 receptor (BDKRB1) were plated at 10,000 cells/well in a 96-well plate or 2,000 cell/well in a 384-well plate and stimulated with a control agonist Lys-des-Arg9 Bradykinin for 90 minutes. The chemiluminescent signal was detected and results show similar pharmacology, EC50, and S/B was obtained in both formats.


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