Long-term recovery of LIP levels in K562 cells after acute iron depletion. Calcein-loaded cells were resuspended in HBS and the fluorescence was monitored for 10 to 20 minutes. At 0 time, 100 μmol/L SIH was added for 10 minutes (labeled as ISAH); cells were then washed free of chelator and resuspended in recovery medium lacking SIH. The cells were incubated either alone (recov: con.) or containing the indicated additives, as in Fig 1. In some experiments, cells were incubated with SIH for 30 minutes before washing (ISAH pre: 30’ recov: Con; ISAH pre 30’ recov: Leup.). At the indicated time points, intracellular LIP concentration was measured as described.