LoVo, SNU-407, DLD-1, SNU-638, AGS, KPL-4, and SK-BR-3 cells were obtained from the Korean Cell Line

Bank (Seoul, Korea). LoVo, SNU-407, DLD-1, SNU-638, AGS, KPL-4, and SK-BR-3 cells were maintained in RPMI 1640 medium supplemented with 10% fetal bovine serum (Gibco, Grand Island, NY, USA) and an antibiotic cocktail (100 U/mL penicillin and 100 μg/mL streptomycin), and were subcultured by trypsinization every 3–4 days. Cells were grown at 37°C and 5% CO2 in humidified air. Two-dimensional gel electrophoresis (2-DE) analysis was performed as described previously [10]. A 0.15-mg protein sample was applied to 13-cm immobilized nonlinear gradient strips (pH 3–10), focused at 8,000 V within 3 hours, and separated on 10% polyacrylamide gels (Serva, Heidelberg, Germany; Bio-Rad). Cell Cycle inhibitor The 2-DE gels were stained with Colloidal Coomassie Blue (Invitrogen, Carlsbad, CA, USA) see more for 24 hours and then

destained with deionized water. Proteins showing abnormal expression were subjected to matrix-associated laser desorption/ionization–mass spectroscopy (MALDI-MS) analysis for identification. After preincubation of LoVo cells (1×106 cells/mL) for 18 hours, G-Rp1 (0–60μM) was added to the cell suspensions and incubated for 24 hours. The cytotoxic effect of G-Rp1 was then evaluated using a conventional MTT assay, as previously reported [11] and [12]. Three hours prior to culture termination, 10 mL MTT solution (10 mg/mL in phosphate-buffered saline, pH 7.4) was added, and the cells were continuously cultured until termination of the experiment. Incubation was halted by addition of 15% sodium dodecyl sulfate (SDS) into each well, solubilizing the formazan [13]. The absorbance at 570 nm (OD570–630) was measured using a Spectramax 250 microplate reader (BioTex, Bad Friedrichshall, mafosfamide Germany). Flow-cytometric analysis for PI staining was performed as described previously [14] and [15]. LoVo (106) cells were washed with PBS, fixed in ethanol, suspended in PI solution (1 mg/mL

RNase A, 50 micro g/mL PI, and 0.1% Triton X-100 in 3.8mM sodium citrate) and incubated on ice for 30 minutes in the dark. After washing three times with fluorescence activated cell sorting (FACS) buffer, PI fluorescent intensity was analyzed on a FACScan (Becton Dickinson, Franklin Lakes, NJ, USA). LoVo cells incubated with G-Rp1 were harvested and suspended in 0.5 mL sample buffer consisting of 40mM Tris, 5M urea (Merck, Darmstadt, Germany), 2M thiourea (Sigma–Aldrich), 4% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (Sigma–Aldrich), 10mM dithiothreitol (Merck), 1mM EDTA (Merck), and a mixture of protease inhibitors (Roche Diagnostics, Basel, Switzerland) for 45 minutes at room temperature.