BMC Cancer 2001, 1:19 http://www.biomedcentral.com/1471-2407/1/19 has been described in Du-145 prostate cancer cells [42]. Competing interests Du-145 cells do not make IL-6; nor are they dependent None declared. upon it for continued proliferation in vitro. However, they were dependent upon STAT3 activation for survival, as demonstrated by experiments in which anti-sense oli- gomucleotides for STAT3 were incoporated by Du-145 cells [42]. We are currently performing similar experi- ments to determine if IL-6 is a necessary ligand for the activation and survival of NRP-154 cells. In summary, we have demonstrated that a major differ- ence between NRP-152 and NRP-154 cells is that NRP- 154 cells over-express the gene for STAT3, relative to NRP-152 cells, and untreated NRP-154 cells. Further- more, NRP-154 cells express constitutively-activated STAT3, while NRP-152 cells do not. Moreover, we found that while both cell lines synthesized IL-6 constitutively, only the IL-6 production of NRP-152 cells was inhibited by dexamethasone treatment (Figure 5). Finally, we demonstrated that while both cell lines expressed the IL- 6 receptor on their surfaces, the patterns were different. NRP-154 cells had a subpopulation of cells which did not stain with anti-IL-6 receptor Ab, while all the NRP-152 cells stained with Ab to the IL-6 receptor. Although the results presented above give us more insight into the role of IL-6 in PCA, they do not tell us if constitutive STAT3 activation is a determining factor in the change to pros- tate neoplasia, or if anti-apoptotic factors induced by STAT3 play a role in prostatic neoplasia. Conclusions We have shown that NRP-152 and NRP-154 cells exhibit fundamental differences in the regulation of IL-6 pro- duction by dexamethasone, and in the requirement for JAK2-mediated events for survival. 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