I n this issue of the JCI, two reports provide intriguing new information on the role of the inflammatory cytokine IL-6 in breast and lung cancer. The study by Sansone et al. implicates IL-6 in the instigation of malignant properties in breast cancer stem cells (see the related article beginning on page 3988). The study by Gao et al. identifies mutant variants of EGFR as inducers of IL-6 in lung adenocarcinomas (see the related article beginning on page 3846). These studies add to our understanding of potential roles for IL-6 in cancer and further motivate investigations of IL-6–targeted chemotherapeutics.