Real-time PCR (RT-PCR)
Chondrocytes were pretreated with empagliflozin (0, 1, and 5 μM) for 2 h, and followed by incubating with IL-1β (10 ng/ml) for 24 h. Afterward, RNAiso reagent (Takara, China) was used to extract total RNA from chondrocytes. The total RNA was reversely transcribed into cDNA with cDNA synthesis kit (Takara). SYBR Green PCR Master Mix (Takara) was used for RT-PCR with an ABI StepOnePlus System (Applied Biosystems, UK). The primers used for the RT-PCR were shown in Table 1.