Regulating gene expression

Cells with largely the same genome can behave differently because they express different sets of genes. Regulation can affect transcription, RNA processing and stability, translation, or protein activity. A gene being present does not mean it is equally active in every cell. A signal may increase transcription of an enzyme-coding gene, producing more messenger RNA. However, RNA abundance alone does not always predict active protein amount because later control steps also matter. Interpret measurements at the level they actually measure.