IL6 and neoplasm: Cytokine involvement is suggested by the high dependency of KS spindle cells in vitro on cytokines for growth, exposure to these required cytokines in vitro induces a morphological shift to the classic spindle KS shape in endothelial cells, and high levels of proinflammatory cytokines including interleukin 1α (IL-1α), IL-1β, and IL-6 are found within the KS tumor microenvironment (7).