a, Representative live cell imaging of the Cu probe Ctrl-CF4 every ten minutes for 60 minutes from MEFs treated with vehicle (VEH) or amino acid deprivation (-AA). Scale bar, 100 μm. b, Mean Ctrl-CF4 fluorescence intensity (FI) ± s.e.m. versus time (minutes, min) from MEFs treated with VEH or -AA normalized to t=0, five minutes. n=30 individual cells. Results were compared using a two-way ANOVA followed by a Sidak’s multi-comparisons test. c, Schematic of immunofluorescence-based approach to access autophagosome formation. d, Schematic of flow cytometry-based approach to access autophagosome number. e,f, Scatter dot plot with bar at mean GFP-LC3 fluorescent intensity ± s.e.m. analyzed by flow cytometry from MEFs stably expressing EGFP-LC3B treated VEH or increasing concentrations of Cu chelator TTM (e) or Fe chelator DFO (f). n=9 biologically independent samples. Results were compared using a one-way ANOVA followed by a Dunnett’s multi-comparisons test. *, P=0.0148; ****, P<0.0001.