Quantitative detection of endolysosomal activity using flow cytometry. (a) Representative image of green fluorescent protein (GFP)-Rab7 cells, exposed to full medium (FM) or nutrient deprivation (ND) medium for 6 h ± bafilomycin A1 (Baf). (b) Western blot analysis of wild-type cells, exposed to FM or ND ± Baf for 6 h. Cell lysates were analyzed for Rab7 and β-actin. (c) Histograms show distribution of GFP-Rab7 fluorescence intensity after 6 h (upper row) or 16 h (lower row) incubation with FM or ND ± Baf. (d) Diagram represents mean fluorescence intensity (relative to fluorescence intensity under FM = 1) of GFP-Rab7 for 1 to 16 h incubation with FM/ND ± Baf.