Immediate Early Response 2 (IER2)

ETR101, a human homolog of rat pip92, is a cellular immediate early gene induced by extracellular stimuli such as serum growth factors. ETR101 encodes a short-lived, proline-rich protein (ETR101) exhibiting no significant sequence similarity to any other known protein, and little is known about its function.

Immediate early genes (IEGs) are genes which are activated transiently and rapidly in response to a wide variety of cellular stimuli. They represent a standing response mechanism that is activated at the transcription level in the first round of response to stimuli, before any new proteins are synthesized. Thus IEGs are distinct from "late response" genes, which can only be activated later following the synthesis of early response gene products. Thus IEGs have been called the "gateway to the genomic response".