Transcription regulation is activated by extracellular signals. One example of this is when insulin from outside the cell binds to an insulin receptor embedded in the plasma membrane.

The extracellular signal begins a signal cascade within the cell. The signal is most commonly transferred from one protein to another by the addition of a phospate group, a process known as phosphorylation.

The signal is transferred through a series of proteins before finally reaching JNK, a protein that interacts with a specific transcription factor.

Transcription only occurs within the nucleus of the cell, so the final protein in the signal pathway must be transported inside the nucleus.

JNK must enter the nucleus through a nuclear pore, a transport complex embedded in the nuclear envelope.