Control of radiation-induced G1 arrest by cell-substratum interactions.

Ionizing radiation has been reported to cause an irreversible, senescence-like G1 arrest in human fibroblasts, which is accompanied by elevated p21CIP1 amounts. In further support of a senescence-like arrest, we show that expression of p53 and cyclin D1 is elevated in gamma-irradiated, arrested fibroblasts. However, we also demonstrate that the arrest is reversible if the irradiated cells are trypsinized and replated, which may implicate cellular-extracellular matrix interactions in cell cycle control after irradiation.