Effects of YY1 on the tumor growth and metastasis of BXPC-3 cells in vivo. (a) BXPC-Scramble shRNA and BXPC-YY1 shRNA cells were bilaterally injected into the flank region of the mice (1.5 × 106 cells/100 μl per flank). After injection, the length and width of the tumors were measured every week. The volume of the tumors was calculated using the formula (width2 × length)/2. The data are presented as means ± SD of 16 tumors for each group. (b) HE staining of the subcutaneous tumors excised four weeks later. Scale bar, 100 μm. (c) Three tumors from each group were resected, RNA was extracted and YY1 expression was measured using qRT-PCR. (d) BXPC-Vector and BXPC-YY1 cells (1.5 × 106 cells/100 μl) were separately injected into the tail vein of each mouse. Four weeks later, lung and liver metastases were evaluated by macroscopic observation and by histomorphology under microscopy. Scale bar, 100 μm. The arrows indicate the metastases. (* represents p < 0.05, # represents p < 0.001, compared with the control group).