2.6. RT-PCR

We obtain the total RNA using RNA Purification Kit (Sangon Biotech, China) and assess the concentration and purity of the total RNA samples in a UV spectrophotometer. The primers for Fbxo21, Nr2f2 and Gapdh were as follows: Fbxo21 (forward 5'-CACGTTCCTTGTAATGGCTTCA-3', reverse 5'-ACGACTCATAGTCATCTGGCTG)-3'; Nr2f2 (forward 5'-TCATGGGTATCGAGAACATTTGC-3', reverse 5'-TTCAACACAAACAGCTCGCTC-3'); Gapdh (forward 5'-GGAGCGAGATCCCTCCAAAAT-3', reverse 5'-GGCTGTTGTC-ATACTTCTCATGG-3'). All experimental procedures were performed according to the instructions in the RT-PCR Kit (Sangon Biotech, China).