Cardiac glycosides are novel and specific inducer of autophagic flux. Diagrams showing autophagic activity (upper row), endolysosomal turnover (middle row) and lysosomal activity (bottom row), determined by flow cytometric quantification of fluorescence intensities of mCherry-green fluorescent protein (GFP) (tandem)-microtubule-associated protein 1 light chain 3 B (LC3), GFP-Rab7 and LysoTracker Red (LTR), respectively. Data was normalized as described in Materials and methods (including normalization to control (Ctr) constructs). Values represent fold changes in relation to full medium (FM) control condition. Drugs have been used at indicated concentrations under FM for 6 h. *P < 0.05, **P < 0.01, ***P < 0.001.