B. Hits from (A) tested for interaction with commercially available constructs quantified with bimolecular fluorescence complementation (BiFC) via flow cytometry. HEKS1/S2-/- were transfected with STIM1-YFPC (black) or STIM1A-YFPC (red) in combination with POI-YFPN and screened for YFP+ cells via FACS, results (mean ± SD) from three transfections with each 10.000 sorted cells. 