inst IMP3 at 4C overnight. Negative controls were done by replacing the primary antibody with nonimmune IgG. IMP3 expression was recorded PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19775295 as negative or positive after visual assessment by a genitourinary pathologist without prior knowledge of patient UPF 1069 price outcome. Positive staining of IMP3 was defined as dark brown cytoplasmic staining pattern in the tumor cells, which can be easily observed at low-power magnification. Scant fine granular background staining of epithelial cells, which cannot be seen at low-power magnification or no staining was considered negative. Statistical analysis The association between IMP3 expression and the tumor clinicopathologic parameters was analyzed by Fisher’s exact test for categorical variables with 2 levels; Cochran-Armitage trend test for categorical factors with >2 levels; and Wilcoxon rank sum test for measured variables. Kaplan-Meier curves were used to observe the associations of IMP3 expression with clinical outcomes. Recurrence-free survival was defined as the interval from diagnosis to documented recurrence, while overall survival was measured from diagnosis to death or last contact. Patients who had not recurred or who died without evidence of recurrence were censored at their last cancer assessment. The magnitudes of these associations were evaluated using Cox proportional hazards regression models and summarized with hazard ratios and their 95% confidence intervals. The significance of the 
interactions was tested by Wald test. Statistical analyses were performed using the SAS 9.2 software package. All tests were 2-sided and p<0.05 was considered statistically significant. Results IMP3 promotes cell migration and invasion in RCC cells As previous studies showed, IMP3 protein expression was significantly associated with RCC metastasis. We speculated that IMP3 may play a role in the invasion of RCC cells. First, the expression of IMP3 in RCC cell lines and HKC cells were examined. As shown in Fig 1. 1A, IMP3 expression was increased in RCC cell lines compared to HKC cells. In addition, Caki-1 cells stably expressing IMP3 by retroviral transduction and Achn cells PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19777456 with stable knockdown of IMP3 were established. We then assessed the effect of IMP3 on cell migration and invasion by Transwell assays. Overexpression of IMP3 in Caki-1 cells significantly promoted cell migration and invasion. In the present investigation, we identified a novel mechanism that IMP3 controls RCC progression by promoting RCC cell migration and invasion via activation of NF-B pathway. In addition, we validated the use of IMP3 as a prognostic marker for localized CCRCC. Although numerous descriptive studies suggested that IMP3 expression correlates with tumor aggressiveness in a variety of malignancies, the role of IMP3 in modulating tumor cellular functions was poorly understood. To our knowledge so far there was no report on mechanisms underlying IMP3 regulation of RCC progression. Our data showed that IMP3 promotes RCC cell migration and invasion, which was consistent with previous findings of IMP3 in breast carcinoma. The EGFR signaling pathway was shown to regulate the expression of IMP3 and is involved in IMP3 promotion of breast cancer cell migration and invasion by up-regulation of CD164 and matrix metalloproteinase 9 . However, we did not demonstrate EGF regulation on IMP3 expression in Caki-1 cells, suggesting that IMP3 in RCC may not function through EGFR signaling pathway. Intriguingly, we identified that IMP3 activa