HPRT1 and colitis: The expression levels of the least stable genes (Actb, Gapdh, Hmbs, Oaz1, β2m, Trfc) in the DNBS experimental colitis group (DNBS + Ethanol 30%) were significantly down regulated or unregulated compared to the control groups (PBS 1%, DNBS + PBS 1%, Ethanol 30%) while the most stable genes (Rplp0, Nono, Eef2, Tbp, Hprt, Ppia, Gusb) did not demonstrate any significant change (Fig. 6).