PACT is a pro-apoptotic protein, which functions via the activation of protein kinase, PKR (protein kinase, RNA-activated). PKR is an interferon (IFN) -induced serine-threonine protein kinase that plays a central role in IFN's antiviral and antiproliferative activities. PKR activation in cells leads to phosphorylation of the subunit of the protein synthesis initiation factor 2 (eIF2), inhibition of protein synthesis, and apoptosis. In the absence of virus infections, PKR is activated by its activator PACT (protein activator of PKR), especially in response to diverse stress signals. Overexpression of PACT in cells causes enhanced sensitivity to stress-induced apoptosis. Here, we have examined PACT expression in different mouse tissues and evaluate its possible role in regulating apoptosis. PACT is expressed at high levels in colonic epithelial (CE) cells, especially as they exit the cell cycle and enter an apoptotic program. PACT expression also coincides with the presence of active PKR and phosphorylated eIF2. These results suggest a possible role of PACT mediated PKR activation in the regulation of epithelial cell apoptosis in mouse colon. In addition, transient overexpression of PACT in a non-transformed intestinal epithelial cell line leads to induction of apoptosis, further supporting PACT's role in inducing apoptosis.