on rate of tumor growth using the following equation: IR = . The relative body weight of mice was calculated using the Wt/W0 index, where Wt was the body weight on the day of measurement, and W0 was the body weight at the first day of treatment. The change in body weight on days 1 and 20, representing the start and end of the experiment, respectively, was used to evaluate and analyze the effects of drugs on the body weight. Cell culture Human gastric adenocarcinoma SGC7901 cells were cultured in the central laboratory of Shengjing Hospital Affiliated to China Medical University, and adriamycin-resistant SGC7901/ ADR cells were gifted from Institute of Digestive Diseases in Xijing Hospital Affiliated to Fourth Military Medical University. Human gastric adenocarcinoma SGC7901 cells and adriamycin-resistant SGC7901/ADR cells were cultured in RPMI-1640 medium supplemented with 10% FBS and antibiotics with 5% CO2 in a humidified incubator at 37uC. ADR was added to the SGC7901/ADR cell culture medium to PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19675955 help maintain their MDR. Cells in the logarithmic growth phase were centrifuged and diluted with RPMI-1640 medium to prepare single-cell suspensions with a concentration of 2.56106/ml for seeding. Establishment of PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19674121 a nude mice xenograft model The in vivo antitumor effect of PAB was examined in a murine xenograft model. For the model, 4-6-week-old male and female immunodeficient BALB/c mice, weighing 18 to 22 g, were purchased from Beijing HFK Bioscience Co., Ltd. and kept in accredited facilities under 
standard conditions for rodents in the Department of Laboratory Animal Science. Fifty mice were selected and randomly assigned into two groups. A total of 25 mice were subcutaneously Immunohistochemical staining for expression of Cox-2, PKC-a and P-gp Tumor specimens were fixed with paraformaldehyde, processed routinely by embedding in paraffin, and then sliced into 4-mm sections. Following hematoxylin and eosin staining, cells of the gastric cancer xenografts were observed under a light microscope. The expression levels of Cox-2, PKC-a and P-gp in harvested tumor cells were determined using the SP method. Briefly, after being dewaxed and rehydrated, slides were incubated in 0.3% H2O2 solution and dried in a microwave in citric acid Inhibitory Effect of Pseudolaric Acid B buffer for 15 min to retrieve antigens. The slices were blocked with normal goat serum for 30 min at 37uC and probed with a rabbit monoclonal antibody to Cox-2 and mouse monoclonal antibodies to PKC-a and P-gp at 4uC overnight. Biotinylated anti-rabbit IgG and anti-rat IgG were added and incubated at 37uC for 30 min before enzyme conjugated HRP-streptavidin was added. In addition, 3, 3′-diaminobenzidine was used as the chromogen. Slides were counterstained with hematoxylin, dehydrated in alcohol, and mounted on neutral balsam. Controls were prepared using secondary antibodies only. Five fields of each section from every mouse in each group were selected for image collection. The Relebactam manufacturer results were analyzed and compared statistically using NIS-Elements Br 3.0 software, and the average optical density was obtained to quantify the expression levels of Cox-2, PKC-a and P-gp. Western blot of Cox-2, PKC-a and P-gp in nude mice xenografts A total of 100 mg of fresh-frozen tumor tissues from at least three mice of each group were weighed and supplemented with radio immunoprecipitation assay lysis buffer. After pulverized using scissors, extracts were homogenized using ultrasound. After centri
