Molecular effectors involved in G1/S arrest, inhibition of proliferation, apoptosis, and metastasis suppression modulated by iron deprivation including: down-regulation of p21CIP1/WAF1 protein and cyclin D1 protein, decreased activity of ribonucleotide reductase, increased p53 protein expression, increased expression of the metastasis suppressor protein Ndrg-1, and the up-regulation of the apoptosis-inducing protein NIP3. Both NIP3 and Ndrg-1 are targets of the hypoxia-inducible factor-1α (HIF-1α) transcription factor. Other HIF-1α targets are probably also involved in the iron-depletion–induced inhibition of proliferation and induction of apoptosis. See the complete figure in the article beginning on page 752.