(Corning) and transfected with 1.5 μg of a CIRTS expression vector
and 1.3 μg of a gRNA expression vector. After 48 h, the cells were
washed twice with ice-cold PBS and lysed in 50 μL RIPA buffer (50 mM
Tris, 150 mM NaCl, 0.5% deoxycholate, 2% SDS, pH 7.4) supplemented with
protease inhibitors. After 30 min room temperature incubation, the
concentration was measured by BCA assay (Thermo Scientific). 35 μg
protein was boiled in protein loading buffer (50 mM Tris pH 6.8, 2% SDS, 10%
glycerol, 0.05% bromphenol blue, 100 mM DTT) for 10 min at 95 °C and
loaded onto a 12% SDS PAGE gel. After stacking at 70 V, the gel was run at
120 V until the dye front reached the bottom, and the proteins were
transferred onto a PVDF membrane (Millipore) and blocked in 5% nonfat milk
in TBST. Proteins were then detected using 1:500 mouse anti-CypB antibody
(Santa Cruz), followed by 1:1000 anti-mouse HRP-conjugated antibody (Santa
Cruz). The loading control GAPDH was visualized using 1:5000 HRP-conjugated
anti-GAPDH antibody (Proteintech). Membranes were imaged on a Fluor Chem R
(Protein Simple) imager after incubation with Super Signal West Pico Plus
(Thermo Scientific).