Figure 3. Effects of ZC88 on the viability of several human tumor cell lines with or without hERG K⁺ channel. (A) and (B), Expression of hERG channel mRNA and protein in several tumor cell lines were identified by RT-PCR (A) and western blot analysis (B), respectively. (C) The cell lines 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 SH-SY5Y or HT29 cells. (n = 3 individual experiments; M: DNA marker, 1: SH-SY5Y, 2: HT-29, 3: A549, 4: H1299, 5: H157).