IC50s were calculated in GraphPad Prism 5 (GraphPad Software, USA). Results for compounds dissolved in DMSO were normalised against corresponding DMSO controls prior to IC50 determination, which are given as the final concentration of compound in the 20 µl reaction volume. Cell lines. HAP1 cells [male] were obtained from Horizon Discovery and grown in IMDM media supplemented with 10% fetal bovine serum (FBS). All cells were cultured at 37 °C in a 5% CO2 atmosphere.