2.12. RNA extraction and quantitative real-time PCR

Total RNA was extracted from tissues and cells using TRIzol reagent (Invitrogen, Carlsbad, CA, USA). The purity and quantity of RNA was determined by measuring the absorbance at 260/280 nm using a SmartSpec Plus Spectrophotometer (Bio-Rad Laboratories, Inc., Hercules, CA, USA). Reverse transcription was carried out using the ReverTra Ace qPCR RT Kit (TOYOBO Life Science, Shanghai, China), according to the manufacturer’s instructions. qRT-PCR was performed using the Bestar SYBR Green qPCR Master Mix (TOYOBO) on a Bio-Rad S1000 system. For quantitative RT-PCR, GAPDH was used as an endogenous control, using the 2−^ΔΔCT method. All primer sequences are listed in Supplementary Table 1 .