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U266 and U937 cells (1 × 10⁶ cells/mL) were treated with indicated concentrations of SM (25 or 50 µg/mL) for 24 h. Then, the cells were lysed with RIPA buffer (1 M EDTA, 1 mM Na₃VO₄, 1 mM NaF, 50 mM Tris-HCl, pH 7.4, 150 mM NaCl, 1% NP-40, 0.25% sodium deoxycholic acid) containing a protease inhibitors cocktail (Amresco, Solon, OH, USA). The protein supernatant was collected and quantified for protein concentration by using an RC DC protein assay kit II (Bio-Rad, Hercules, CA, USA). The proteins (30 µg) were separated via SDS-polyacrylamide gel electrophoresis and transferred to nitrocellulose membranes that were blocked with 5% skim milk in Tris-buffered saline with 0.05% Tween 20 and incubated with the required antibodies. Primary antibodies, including cleaved PARP (1:1000, 89 kDa), CHOP (1:500, 27 kDa), P-eIF2α (1:500, 38 kDa) (Cell Signaling, Beverly, MA, USA), P-ATF4 (1:500, 39 kDa) (Thermo Fisher, Waltham, MA, USA), P-PERK (1:500, 125 kDa) (Thermo Fisher, Waltham, MA, USA), c-Jun (1:1000, 39 kDa), and β-actin (1:1000, 43 kDa) (Santa Cruz, Dallas, TX, USA), were used at a 1:500~1000 dilution (5% bovine serum albumin) and secondary antibodies at a 1:1000 dilution (5% skim milk) (Santa Cruz, Dallas, TX, USA). After detected protein bands were visualized by Hybond ECL (Amersham Pharmacia, Piscataway, NJ, USA), the blots were scanned.

The detailed procedures for the preparation of cellular lysates and the Western blot analysis have been described previously.¹⁵ The primary antibodies used in this study were as follows: HIF1α (36169S, CST, USA), Ero1α (3264S, CST, USA; 702709, Thermo Fisher, USA), p‐PERK (PA5‐102853, Thermo Fisher, USA), PERK (PA5‐120620, Thermo Fisher, USA), BIP (ab21685, Abcam, USA), p‐eif2α (3398S, CST, USA), eif2α (5324S, CST, USA), CHOP (2895S, CST, USA), CC3 (19677‐1‐AP, Proteintech, USA), Bax (ab32503, Abcam, USA), Bcl‐2(ab32124, Abcam, USA), SIRT6 (ab191385, Abcam, USA), p‐p65 (ab76302, USA), p65 (ab32536, USA), ICAM‐1 (ab53013, ab171123, Abcam, USA), VCAM‐1 (ab134047, Abcam, USA), VE‐cadherin (ab33168, Abcam, USA) and β‐actin (ab8226, Abcam, USA) was applied as the internal standard substances.