Altogether the residual expression of mb-IL-15 following treatment with anti-IL-15R mAbs, its resistance to acidic treatment and the activation of a reverse signal in response to the soluble receptor suggest the existence of an IL-15 form anchored in an IL-15R independent fashion that could correspond to the trans-membrane IL-15 form recently described on human prostate cancer cells [10]. The gene discussed is IL15; the disease is prostate carcinoma.