<p>(A) 21-BD competition of <sup>3</sup>H-ouabain binding on HeLa cells; the control for maximal binding is represented with a white circle and a long dashed line, competition of ouabain and 21-BD is shown with blue and red circles respectively. (B) Inhibition of rat´s brain hemisphere Na,K-ATPase after 2 h incubation with digoxin (green circles) or 21-BD (red circles). (C) Effect of 21-BD on the Na,K-ATPase activity on proteins expressed in Sf9 insect cells, Na,K-ATPase activity was measured on Sf9 cells expressing the rat α<sub>1</sub> β<sub>1</sub> (orange circles) or β<sub>1</sub> (red circles) after 15 min treatment with the indicated concentrations of 21-BD. (D) Dose-response curve for the effects of 21-DB on Na,K-ATPase activity of mouse kidney membrane preparations. E) Effect of 21-BD (red circles) or digoxin (green circles) on the activity of the Pdr5p transporter.</p
