Discusses Hua Yu and colleagues' report in the "Nature Medicine" which showed that the constitutive activation of the Stat3 transcription factor in tumours inhibit dendritic cell (DC) maturation and prevents the immune system from eliminating the tumour. Effects of blocking Stat3 activation in the B16 mouse tumour cell line; Failure of fibroblasts to express interleukin-6 or Rantes after stimulation with inflammatory mediators; Components of the immune response.