MetAP2 inhibition has been reported to lead to cell cycle arrest in the G1 phase through the inhibition of Rb protein phosphorylation and CdKi p21 accumulation in endothelial cell lines and in several tumor cells, and both p53 and p21 seem to be required for the antiproliferative effect of TNP-470 [24, 30, 48]. The gene discussed is RB1; the disease is neoplasm.