DFP-mediated relocation of iron between cellular compartments: from endosomes to nuclei. H9C2 cells were loaded with the nuclear iron-sensor H-FlDFO and subsequently exposed to preformed complexes of CALG and iron (CALG-Fe, 1:1 ratio) that were taken up by adsorptive pinocytosis into endosomes. The cells containing both labels were then exposed to 50 μM DFP and epifluorescent images were recorded every 5 minutes under fluorescein settings. Representative fields of cell fluorescence are shown at time 0 (A) and after incubation for 20 minutes (B) in the presence of 50 μM DFP. (C) The nuclei (N) and endosomes (E) are indicated by arrows. (D) Mean fluorescence values in r.u. within selected subcellular areas corresponding to endosomes (Di) and nuclei (Dii), using 5 cells per field, calculated for each time-point image and normalized to the initial fluorescence (f/f₀).