Total RNA from frozen mouse colon tissue was isolated using TRI Reagent (Molecular Research Center, Inc., Cincinnati, OH, USA). Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed using the StepOnePlus detection system (Applied Biosystems, Foster City, CA, USA) and the TaqMan One-Step RT-PCR kit containing AmpliTaq Gold® DNA polymerase [23 (link)]. Specific primers and probes were obtained from Applied Biosystems. Fold changes in qPCR expression were calculated by the 2(−ΔΔCT) method [24 (link)].