Differentiation and Maintenance of 3T3-L1 and HEK293 Cells

3T3-L1 and human embryonic kidney 293 (HEK293) cells were purchased from the Korea Cell Line Bank (Seoul, Korea). 3T3-L1 cells were maintained and differentiated as previously described^{36 (link),37} . Briefly, the cells were maintained in Dulbecco’s modified Eagle’s medium (DMEM; Welgene, Korea) supplemented with 10% calf serum and 1% antibiotics at 37 °C in 5% CO₂. Confluent 3T3-L1 cells were incubated for 48 h. Then, the medium was replaced with DMEM supplemented with 10% fetal bovine serum (FBS), dexamethasone (1 µM), insulin (1 µg/ml), and isobutylmethylxanthine (520 µM). After 48 h, the medium was replaced with DMEM supplemented with 10% FBS and insulin (1 µg/ml), and after an additional 48 h, the medium was replaced with DMEM supplemented with 10% FBS. HEK293 cells were maintained in DMEM supplemented with 10% FBS and 1% antibiotics at 37 °C in 5% CO_2.