FIGURE 1.

Identification of ATP1A1 as a component of the machinery mediating unconventional secretion of FGF2. A, mean scores of a selected set of siRNAs used in large scale RNAi screening for gene products involved in FGF2 secretion. A stable HeLa cell line expressing FGF2-GFP in a doxycycline-dependent manner was used to quantify FGF2 secretion as described under “Experimental Procedures.” All isoforms of α- and β-chains of the Na/K-ATPase known in the human genome were targeted with three independent siRNAs. In addition, three siRNAs directed against FGF2 are shown. As a control, a validated siRNA against GFP was used to down-regulate the FGF2-GFP reporter itself. Error bars, S.D. (n = 4). B, expression analysis of all known α- and β-chains of the Na/K-ATPase complex in HeLa cells employing RT-PCR.