Figure 4

Inhibition of keratinocyte mitogenesis by the hIK1 agonist 1-EBIO is not reversed by hIK1 blockers charybdotoxin (ChTX), clotrimazole (CLT) and TRAM-34 (TRAM). Keratinocyte mitogenesis was assessed by measuring tritiated-thymidine incorporation over a 24 hour period. (A) single experiment, representative of four total, showing dose-dependence of 1-EBIO inhibition of mitogenic activity. Mitogenic inhibition was significant (*) at the concentrations of 1-EBIO tested (ANOVA, 95% confidence interval). (B) Cumulative data showing failure of hIK1 blockers ChTX, clotrimazole, and TRAM-34 to reverse the inhibitory effect of 100 μM 1-EBIO on keratinocyte mitogenesis. Percent difference in thymidine incorporation versus untreated control cells plotted with each column representing mean ± SEM of 3–4 experiments. Numbers next to drugs indicate μM concentrations. 100 μM 1-EBIO, with or without hIK1 blockers present, caused significant reductions in thymidine incorporation relative to untreated control cells (indicated by asterisks). That is, blockers did not reverse inhibition due to 1-EBIO which would be expected if 1-EBIO was acting via agonism of hIK1. TRAM-34 itself caused significant proliferative inhibition but only at 1 μM.