A central component of the cellular stress response is p21 WAF1/CIP1 , which regulates cell proliferation, survival, and differentiation. Inflammation and cell stress often up-regulate p21 posttranscriptionally by regulatory mechanisms that are poorly understood. ZO-1-associated nucleic acid binding protein (ZONAB)/DbpA is a Y-box transcription factor that is regulated by components of intercellular junctions that are affected by cytokines and tissue damage. We therefore asked whether ZONAB activation is part of the cellular stress response. Here, we demonstrate that ZONAB promotes cell survival in response to proinflammatory, hyperosmotic, and cytotoxic stress and that stress-induced ZONAB activation involves the Rho regulator GEF-H1. Unexpectedly, stress-induced ZONAB activation does not stimulate ZONAB's activity as a transcription factor but leads to the posttranscriptional up-regulation of p21 protein and mRNA. Up-regulation is mediated by ZONAB binding to specific sites in the 3′-untranslated region of the p21 mRNA, resulting in mRNA stabilization and enhanced translation. Binding of ZONAB to mRNA is activated by GEF-H1 via Rho stimulation and also mediates Ras-induced p21 expression. We thus identify a unique type of stress and Rho signaling activated pathway that drives mRNA stabilization and translation and links the cellular stress response to p21 expression and cell survival.epithelia | RhoGTPases | tight junction | necrosis | apoptosis C ells developed regulatory pathways that are activated in response to proinflammatory challenges, adverse extracellular conditions, and cytotoxic stress to ensure cell survival and tissue integrity. These pathways regulate expression of genes encoding factors required to cope with stress conditions and involve transcription factors that stimulate the synthesis of mRNAs encoding proteins required for specific responses. However, expression of many crucial stress-induced genes is regulated posttranscriptionally by mechanisms that are not well understood.A central regulator of cell proliferation and survival is p21 WAF1/CIP1