Endolysosomes were more numerous and contained higher levels of Fe2+ when located close to the nucleus: (a) Representative confocal image of an U87MG cell labeled with FeRhoNox-1 for [Fe2+]el, LysoTracker for endolysosomes, and DAPI for nuclei. (b) Endolysosomes were more abundant when located closest to the nucleus. (c) The cell depicted in (a) above was reconstructed with Imaris software (version 9.5, Oxford instruments) to demonstrate [Fe2+]el relative to endolysosome locations. (d) Endolysosomes contained higher levels of Fe2+ when located closest to the nucleus. Scale bars are 5 μm. Each data point represents the mean fluorescence intensity of endolysosomes per cell measured from 10 cells (n = 50). (b) F(4, 20) = 433.2, p < 0.0001; (d) F(4, 20) = 191.8, p < 0.0001