The silver-stained proteins of interphasic nucleolar organizer regions as a parameter of cell duplication rate

The relationship between interphasic silver-stained proteins of the nucleolar organizer regions (Ag-NOR proteins) and cell replication rate has been studied in 13 established neuroblastoma cell lines. The quantity of Ag-NOR proteins was measured in silver-stained cells by means of an automated image analyzer. The results indicated that the amount of Ag-NOR proteins is strictly proportional to the proliferative activity of the cells. Cell lines with a difference of only 4 h in doubling time were characterized by a statistically significant difference in Ag-NOR protein amount. The Ag-NOR protein quantity can therefore be used as a parameter for evaluating the cell proliferation rate.