Expression of p21^CIP1/WAF1 protein is increased by lysosomotropic agents in Fe-replete cells, while chelator-induced down-regulation of p21^CIP1/WAF1 can only be effectively rescued by proteasomal inhibitors. (A) MCF-7 cells were incubated for 24 hours at 37°C with either control medium (Con), chloroquine (250 μM), NH₄Cl (15 mM), CH₃NH₂ (15 mM), 311 (25 μM), or the combination of 311 (25 μM) with chloroquine (250 μM), NH₄Cl (15 mM), or CH₃NH₂ (15 mM). (B) MCF-7 cells were incubated for 24 hours at 37°C with either control medium (Con), chloroquine (250 μM), MG132 (20 μM), 311 (25 μM), or 311 (25 μM) combined with either chloroquine (250 μM) or MG132 (20 μM). Cells were harvested and Western blot was performed. Results are representative from 3 experiments formed.