Test compounds were serially diluted into white bottom opaque tissue culture grade 384-well assay plates (Perkin Elmer) using Echo550 (Labcyte) and GSK3β-HiBiT KI HEK293 cells were seeded at a density of 5×10 3 cells per well either in 50 µl of DMEM supplemented with regular 10%FBS (Gibco) or instead 10% Mouse Serum (Balb/C) and plates were incubated for compound treatment in incubators at 37 °C. After 24 hours of compound treatment, HiBiT lytic reagents (Promega) prepared according to manufacturers' instructions were added into plates and luminescence signal was measured on a PheraStar plate reader (BMG) and data analysed using GraphPad Prism (v10.1.2) as previously described above.