['The intestinal mitosis-inhibiting peptide pyroglu-His-GlyOH (pEHG), inhibits normal intestinal epithelial cells and the human colon adenocarcinoma cell line HT-29 and increases the expression of c-fos (1). In this study, we investigated the mechanisms of the growth-inhibiting effects of pEHG.', 'cDNA expression array was hybridized with cDNA from HT-29 cells exposed to pEHG or control. The results were confirmed with Northern blot or real-time PCR.', 'pEHG(1 nM) provoked a significant increase in the expression of the early growth response protein 1 (egr-1) after an incubation of 20 minutes, while c-fos was confirmed up-regulated by the same treatment. We further studied the expression of fosB, c-jun and junB, in the AP-1 complex. fosB was up-regulated 20-fold, but only minor effects on jun variants were observed.'] Does the colon mitosis-inhibitor pyroglutamyl-histidyl-glycine alter expression of immediate-early cancer-related genes in HT-29 cells?