Screen Quest? Fluo-4 No Wash Calcium Assay Kit. Calcium flux assays are preferred methods in drug discovery for screening G protein coupled receptors (GPCR). Screen Quest? Fluo-4 No Wash Calcium Assay Kit provides a homogeneous fluorescence-based assay for detecting the intracellular calcium mobilization. Cells expressing a GPCR of interest that signals through calcium are pre-loaded with Fluo-4 AM which can cross cell membrane. Once inside the cell, the lipophilic blocking groups of Fluo-4 AM are cleaved by non-specific cell esterase, resulting in a negatively charged Fluo-4 dye that stays inside cells, and its fluorescence is greatly enhanced upon binding to calcium. When cells stimulated with screening compounds, the receptor signals release of intracellular calcium, which greatly increase the fluorescence of Fluo-4. This Screen Quest Fluo-4 No Wash Calcium Assay Kit provides an optimized assay method for monitoring G-protein-coupled receptors (GPCRs) and calcium channels. The assay can be performed in a convenient 96-well or 384-well microtiter-plate format and easily adapted to automation.