title: Differences in the response of early and mid or late G1 WI38 cells treated with cyclohexamide to HeLa inducers of DNA synthesis.
abstract: The inducibility of DNA synthesis after treatment with cyclohexamide (CHM) during mitosis and the G1 phase of WI38 cells has been studied in the heterokaryons following fusion with HeLa cells in S phase. Synchronized mitotic cells treated for up to 5 h with CHM were not delayed in the initiation of DNA synthesis in the heterokaryons. The G1 cells treated with CHM for 3-24 h were slow in responding to inducers of DNA synthesis generated by HeLa cells in the heterokaryons. The results suggest that there is a specific point in early G1 that regulates the entry of cells into a cycling state. In the presence of CHM, mitotic cells divide, but the daughter cells fail to enter G1 leading to DNA synthesis, and CHM treatment of G1 cells results in their transient entry into a G0 state.
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D002459:Cell Fusion; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology*; D004261:DNA Replication / Q000187:drug effects*; D006367:HeLa Cells / Q000166:cytology; D006801:Humans; D006822:Hybrid Cells / Q000166:cytology* / Q000187:drug effects; D007700:Kinetics
chemical_list: D003513:Cycloheximide