Frequency of cells with a hematopoietic stem cell phenotype in control, IL-6, or IL-6/soluble IL-6R transgenic mice. The presence of Lin⁻/Sca1⁺/c-kit⁺cells present in bone marrow, spleen, and liver of (□) control mice, (▨) IL-6 transgenic mice, and (▪) IL-6/soluble IL-6R double-transgenic mice was analyzed by FACS.