RNA Extraction and qRT-PCR Analysis

Total RNA was extracted from IPEC-J2 cells by using RNAiso Plus (Takara, San Jose, CA, USA). The final extract was resuspended in RNase-free water, and the RNA concentration and purity were measured with Nanodrop (ThermoFish Scientific, Waltham, MA, USA). Then, cDNA was generated by PrimeScript^TM reagent Kit with gDNA Eraser (Takara, San Jose, CA, USA) following the manufacturer’s protocol. The qRT-PCR primer sequences designed and synthesized by Sangon Biotech are listed in Table 1. The GAPDH gene was used as a standardized internal control. The 2^−ΔΔCT method was used to express the relevant gene mRNA expression data as a fold change [7 (link)].