Quantitative real-time PCR (qRT–PCR) analysis
The total RNA of tissues was efficiently extracted with the EasyPure® RNA Purification Kit (Transgen Biotech, ER701-01, Beijing, China). The obtained total RNAs were used for first-strand cDNA synthesis, and their relative expression was estimated by the q-PCR method (TransStart® Top Green qPCR SuperMix, Transgen Biotech, AQ131-01, Beijing, China) on a CFX96 Touch qPCR System (Bio-Rad Laboratories, Hercules, CA, USA). β-actin was used as an internal reference gene, and the 2