Na/K-ATPase knockdown changes subcellular distribution of Cav1. (A) A representative Western blot shows the amount of α1 in total cell lysates from different cell lines. (B) Total cell homogenate from control (P-11) and knockdown (A4-11 and TCN23-19) cells was fractionated by gradient centrifugation as described under Materials and methods. Fractions (1 ml each) were collected from top to bottom, and equal volume of each fraction was immunoblotted for proteins as indicated. (C) Distribution of different subcellular markers in different fractions: EEA-1 (early endosomes), GM130 (Golgi), Calnexin (ER). A representative blot from P-11 cells is shown. Similar distribution of these markers was detected in the knockdown cells. (D) Cav1 in total cell lysates and fraction 4/5 was analyzed by Western blot. Quantitative data (mean ± SE) from 4–6 independent experiments are shown, **, P < 0.01 in comparison to control.