Phosphatase activities are determined on immunoprecipitates of the phosphatases. Briefly, 2×10⁶ K562 cells are treated for 18 hr with Salubrinal (20 μM), PSI (10 nM), the combination of both drugs or okadaic acid (100 nM). After washing with PBS, cells are lysed for 15 min on ice either in PP1LB (for determination of PP1γ-activity; 20 mM Tris-HCl, pH 7.5, 1% Triton X-100, 10% glycerol, 132 mM NaCl, Roche complete protease inhibitor ) or in RIPA (for PP2A), supplemented with Roche complete protease inhibitor). Cell lysates containing 500 μg (PP1γ) or 300 μg (PP2A) protein are immunoprecipitated overnight at 4°C with 2-3 μg of the appropriate antibodies and then incubated with Protein A-Sepharose. Immunoprecipitates are washed three times in lysis buffer, followed by resuspension in phosphatase assay buffer (PP2A: 20 mM Tris-HCl, pH7.5, 0.1 mM CaCl₂; PP1γ: 50 mM Tris HCl pH 7.0, 0.2 mM MnCl₂, 0.1 mM CaCl₂, 125 μg/mL BSA, 0.05% Tween 20), supplemented with 100 μM 6,8-difluoro-4-methyl-umbelliferyl phosphate (DiFMUP). Precipitates are allowed to react with substrate for 1 hr at 37°C on an Eppendorf Thermoshaker, centrifuged and DiFMU fluorescence is measured on a BioTek Lambda Fluoro 320 microplate reader (360 nm_ex/460 nm_em). Phosphatase activities are given as percent change relative to the control (DMSO treated cells)^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Cellular viability is assessed by the WST-1 colorimetric assay. Assays are performed on 96 well plates with 2×10⁴ K562 cells/well in triplicate with Salubrinal concentrations ranging from 5-75 μM (total volume of 200 μL, 18 hrs). Untreated cells served as negative control sample^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Mice^[2]
Using Balb/c female mice (~nine weeks old), CAIA is induced by intravenous injection of a 2 mg cocktail of ArthritoMAb antibodies on day 0 followed by intraperitoneal injection of 100 μg LPS on day 3. Mice are randomly divided into a placebo group and a Salubrinal-treated group. Salubrinal (2.0 mg/kg) is intravenously administered daily from day 0, while a solvent (49.5% PEG 400 and 0.5% Tween 80 in PBS) is administered to the placebo group.

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

• [1]. Drexler HC. Synergistic Apoptosis Induction in Leukemic Cells by the Phosphatase Inhibitor Salubrinal and Proteasome Inhibitors. PLoS One. 2009;4(1):e4161.  [Content Brief]

  [2]. Hamamura K, et al. Salubrinal acts as a Dusp2 inhibitor and suppresses inflammation in anti-collagen antibody-induced arthritis. Cell Signal. 2015 Apr;27(4):828-35.  [Content Brief]

  [3]. Bryant KF, et al. ICP34.5-dependent and -independent activities of salubrinal in herpes simplex virus-1 infected cells. Virology. 2008 Sep 30;379(2):197-204.  [Content Brief]