A regulatory subunit of phosphoinositide 3-kinase increases the nuclear accumulation of X-box–binding protein-1 to modulate the unfolded protein response

Insulin signals through phosphoinositide 3-kinase (PI3K) to induce cell growth, which often increases protein translation and stress of the endoplasmic reticulum (ER). In two new studies, Umut Ozcan and Ron Kahn and their colleagues now find that in response to insulin signaling, p85α and p85β, the heterodimeric regulatory subunits of PI3K, can increase the nuclear localization of a key transcription factor that resolves ER stress (pages 374–376 and pages 429–437).