Fig. (1) Schematic of biochemical and cellular TR-FRET Ser/Thr-kinase assays. (A) Biochemical KinEASE assay. (B) and (C) Cellular Ser/Thr-kinase assays. Target kinases are overexpressed in combination with cSTK peptide substrates (B) or full-length protein substrates like MEK1 (C). TR-FRET between phospho-specific and epitope-tag targeted antibodies is used to quantify intracellular substrate phosphorylation post lysis.