Figure 4. Effect of ZC88 on the viability of HEK293 cells stably transfected with hERG1. (A) HEK293 cells were transfected with a plasmid of pcDNA3.1 encoding hERG1 or vector only. HEK293 clone expressing hERG1 was identified by western blot analysis with hERG1 antibody. (B) The cell lines stably transfected with hERG1or pcDNA3.1 vector and parental HEK293 cells were respectively treated with ZC88 (3.125–100 μM) for 24 h. Cell viability was determined by SRB assay. The GI₅₀ by ZC88 was calculated with Logistic equation. Data were expressed as mean ± SEM ** p < 0.01, compared with the GI₅₀ of vector-transfected HEK293 cells. (n = 3 individual experiments).