Like a jealous chef, the nucleus guards the recipes for making all the proteins a cell needs. It holds tightly to the original recipe book, written in DNA, doling out copies of the instructions in the form of messenger RNA (mRNA) to the cell's cytoplasm only as they are needed.
But in cancer cells and in cells infected by viruses, those carefully issued orders are often drowned out. Mutations can cause cancer cells to issue garbled directions that result in aberrant proteins. Similarly, viruses flood cells with their own mRNA, hijacking the cells' protein-making apparatuses to make copies of new viruses that can go on to infect other cells.
This article was originally published with the title Killing the Messenger.