Ras expressing mammary tumors exhibit high levels of activated Stat3 and IL-6. (a) Paraffin embedded tumors from MCF10A-Ras cells expressing control (Ras-C) or Stat3shRNA (RasS3sh) were examined by hematoxyline and eosin (H&E), pStat3 and IL-6 by immunohistochemistry. Extracts from MCF10A-Ras expressing control (C) or Stat3 shRNA (S3sh) tumors were analyzed for pStat3 and Tubulin by Western blot analysis. (b) Paraffin embedded tumors from MMTV-promoter driven K-Ras (MMTV-K-Ras) were analyzed by hematoxyline and eosin stain (H&E), for pStat3 by immunohistochemistry and for IL-6 by immunofluorescence. Extracts from normal mammary tissue (N) or MMTV-K-Ras (K-Ras) were analyzed for pStat3, Stat3 and Tubulin.